diff --git a/docs/examples/tree/customized-node.vue b/docs/examples/tree/customized-node.vue
index ca493c27c6..036bb5fce3 100644
--- a/docs/examples/tree/customized-node.vue
+++ b/docs/examples/tree/customized-node.vue
@@ -68,7 +68,7 @@ const append = (data: Data) => {
 
 const remove = (node: Node, data: Data) => {
   const parent = node.parent
-  const children: Tree[] = parent.data.children || parent.data
+  const children: Tree[] = parent?.data.children || parent?.data
   const index = children.findIndex((d) => d.id === data.id)
   children.splice(index, 1)
   dataSource.value = [...dataSource.value]
diff --git a/docs/examples/tree/multiple-times-load.vue b/docs/examples/tree/multiple-times-load.vue
index e3b3cab6f2..669d139181 100644
--- a/docs/examples/tree/multiple-times-load.vue
+++ b/docs/examples/tree/multiple-times-load.vue
@@ -5,11 +5,6 @@
 <script lang="ts" setup>
 import type { LoadFunction } from 'element-plus'
 
-interface Tree {
-  name: string
-  leaf?: boolean
-}
-
 const props = {
   label: 'name',
   children: 'zones',
diff --git a/packages/components/tree/src/model/node.ts b/packages/components/tree/src/model/node.ts
index 4a14205c78..24db8976db 100644
--- a/packages/components/tree/src/model/node.ts
+++ b/packages/components/tree/src/model/node.ts
@@ -1,5 +1,5 @@
-// @ts-nocheck
 import { reactive } from 'vue'
+import { isNil } from 'lodash-unified'
 import {
   hasOwn,
   isArray,
@@ -67,7 +67,7 @@ const reInitChecked = function (node: Node): void {
 const getPropertyFromData = function (node: Node, prop: string): any {
   const props = node.store.props
   const data = node.data || {}
-  const config = props[prop]
+  const config = (props as any)[prop]
 
   if (isFunction(config)) {
     return config(data, node)
@@ -83,17 +83,17 @@ let nodeIdSeed = 0
 
 class Node {
   id: number
-  text: string
+  text: string | null
   checked: boolean
   indeterminate: boolean
   data: TreeNodeData
   expanded: boolean
-  parent: Node
+  parent: Node | null
   visible: boolean
   isCurrent: boolean
-  store: TreeStore
-  isLeafByUser: boolean
-  isLeaf: boolean
+  store!: TreeStore
+  isLeafByUser: boolean | undefined = undefined
+  isLeaf: boolean | undefined = undefined
   canFocus: boolean
 
   level: number
@@ -106,9 +106,9 @@ class Node {
     this.text = null
     this.checked = false
     this.indeterminate = false
-    this.data = null
+    this.data = null as unknown as TreeNodeData
     this.expanded = false
-    this.parent = null
+    this.parent = null as Node | null
     this.visible = true
     this.isCurrent = false
     this.canFocus = false
@@ -168,7 +168,12 @@ class Node {
     const defaultExpandedKeys = store.defaultExpandedKeys
     const key = store.key
 
-    if (key && defaultExpandedKeys && defaultExpandedKeys.includes(this.key)) {
+    if (
+      key &&
+      !isNil(this.key) &&
+      defaultExpandedKeys &&
+      defaultExpandedKeys.includes(this.key)
+    ) {
       this.expand(null, store.autoExpandParent)
     }
 
@@ -186,8 +191,7 @@ class Node {
     }
 
     this.updateLeafState()
-    if (this.parent && (this.level === 1 || this.parent.expanded === true))
-      this.canFocus = true
+    if (this.level === 1 || this.parent?.expanded === true) this.canFocus = true
   }
 
   setData(data: TreeNodeData): void {
@@ -214,7 +218,7 @@ class Node {
     return getPropertyFromData(this, 'label')
   }
 
-  get key(): TreeKey {
+  get key(): TreeKey | null | undefined {
     const nodeKey = this.store.key
     if (this.data) return this.data[nodeKey]
     return null
@@ -265,11 +269,11 @@ class Node {
     if (!(child instanceof Node)) {
       if (!batch) {
         const children = this.getChildren(true)
-        if (!children.includes(child.data)) {
+        if (!children?.includes(child.data)) {
           if (isUndefined(index) || index < 0) {
-            children.push(child.data)
+            children?.push(child.data)
           } else {
-            children.splice(index, 0, child.data)
+            children?.splice(index, 0, child.data)
           }
         }
       }
@@ -329,8 +333,8 @@ class Node {
     this.updateLeafState()
   }
 
-  removeChildByData(data: TreeNodeData): void {
-    let targetNode: Node = null
+  removeChildByData(data: TreeNodeData | null): void {
+    let targetNode: Node | null = null
 
     for (let i = 0; i < this.childNodes.length; i++) {
       if (this.childNodes[i].data === data) {
@@ -344,11 +348,11 @@ class Node {
     }
   }
 
-  expand(callback?: () => void, expandParent?: boolean): void {
-    const done = (): void => {
+  expand(callback?: (() => void) | null, expandParent?: boolean): void {
+    const done = () => {
       if (expandParent) {
         let parent = this.parent
-        while (parent.level > 0) {
+        while (parent && parent.level > 0) {
           parent.expanded = true
           parent = parent.parent
         }
@@ -396,8 +400,8 @@ class Node {
     })
   }
 
-  shouldLoadData(): boolean {
-    return this.store.lazy === true && this.store.load && !this.loaded
+  shouldLoadData() {
+    return Boolean(this.store.lazy === true && this.store.load && !this.loaded)
   }
 
   updateLeafState(): void {
@@ -481,7 +485,7 @@ class Node {
     }
   }
 
-  getChildren(forceInit = false): TreeNodeData | TreeNodeData[] {
+  getChildren(forceInit = false): TreeNodeData | TreeNodeData[] | null {
     // this is data
     if (this.level === 0) return this.data
     const data = this.data
@@ -508,13 +512,13 @@ class Node {
     const newData = (this.getChildren() || []) as TreeNodeData[]
     const oldData = this.childNodes.map((node) => node.data)
 
-    const newDataMap = {}
-    const newNodes = []
+    const newDataMap: Record<TreeKey, TreeNodeData> = {}
+    const newNodes: TreeNodeData[] = []
 
     newData.forEach((item, index) => {
       const key = item[NODE_KEY]
       const isNodeExists =
-        !!key && oldData.findIndex((data) => data[NODE_KEY] === key) >= 0
+        !!key && oldData.findIndex((data) => data?.[NODE_KEY] === key) >= 0
       if (isNodeExists) {
         newDataMap[key] = { index, data: item }
       } else {
@@ -524,7 +528,7 @@ class Node {
 
     if (!this.store.lazy) {
       oldData.forEach((item) => {
-        if (!newDataMap[item[NODE_KEY]]) this.removeChildByData(item)
+        if (!newDataMap[item?.[NODE_KEY]]) this.removeChildByData(item)
       })
     }
 
@@ -536,7 +540,7 @@ class Node {
   }
 
   loadData(
-    callback: (node: Node) => void,
+    callback: (data?: TreeNodeData[]) => void,
     defaultProps: TreeNodeLoadedDefaultProps = {}
   ) {
     if (
@@ -547,7 +551,7 @@ class Node {
     ) {
       this.loading = true
 
-      const resolve = (children) => {
+      const resolve = (children: TreeNodeData[]) => {
         this.childNodes = []
 
         this.doCreateChildren(children, defaultProps)
diff --git a/packages/components/tree/src/model/tree-store.ts b/packages/components/tree/src/model/tree-store.ts
index c3a98eaff0..c1c6250e47 100644
--- a/packages/components/tree/src/model/tree-store.ts
+++ b/packages/components/tree/src/model/tree-store.ts
@@ -1,6 +1,6 @@
-// @ts-nocheck
 import { nextTick } from 'vue'
-import { hasOwn, isObject, isPropAbsent } from '@element-plus/utils'
+import { isNil } from 'lodash-unified'
+import { NOOP, hasOwn, isObject, isPropAbsent } from '@element-plus/utils'
 import Node from './node'
 import { getNodeKey } from './util'
 
@@ -17,22 +17,22 @@ import type {
 } from '../tree.type'
 
 export default class TreeStore {
-  currentNode: Node
-  currentNodeKey: TreeKey
+  currentNode: Node | null
+  currentNodeKey: TreeKey | null
   nodesMap: TreeStoreNodesMap
-  root: Node
-  data: TreeData
-  lazy: boolean
-  load: LoadFunction
-  filterNodeMethod: FilterNodeMethodFunction
-  key: TreeKey
-  defaultCheckedKeys: TreeKey[]
-  checkStrictly: boolean
-  defaultExpandedKeys: TreeKey[]
-  autoExpandParent: boolean
-  defaultExpandAll: boolean
-  checkDescendants: boolean
-  props: TreeOptionProps
+  root!: Node
+  data!: TreeData
+  lazy = false
+  load?: LoadFunction
+  filterNodeMethod?: FilterNodeMethodFunction
+  key!: TreeKey
+  defaultCheckedKeys?: TreeKey[]
+  checkStrictly = false
+  defaultExpandedKeys?: TreeKey[]
+  autoExpandParent = false
+  defaultExpandAll = false
+  checkDescendants = false
+  props!: TreeOptionProps
 
   constructor(options: TreeStoreOptions) {
     this.currentNode = null
@@ -56,10 +56,14 @@ export default class TreeStore {
 
     if (this.lazy && this.load) {
       const loadFn = this.load
-      loadFn(this.root, (data) => {
-        this.root.doCreateChildren(data)
-        this._initDefaultCheckedNodes()
-      })
+      loadFn(
+        this.root,
+        (data) => {
+          this.root.doCreateChildren(data)
+          this._initDefaultCheckedNodes()
+        },
+        NOOP
+      )
     } else {
       this._initDefaultCheckedNodes()
     }
@@ -74,7 +78,12 @@ export default class TreeStore {
         : (node as Node).childNodes
 
       for (const [index, child] of childNodes.entries()) {
-        child.visible = filterNodeMethod.call(child, value, child.data, child)
+        child.visible = !!filterNodeMethod?.call(
+          child,
+          value,
+          child.data,
+          child
+        )
 
         if (index % 80 === 0 && index > 0) {
           await nextTick()
@@ -95,7 +104,7 @@ export default class TreeStore {
       if (!value) return
 
       if ((node as Node).visible && !(node as Node).isLeaf) {
-        if (!lazy || node.loaded) {
+        if (!lazy || (node as Node).loaded) {
           ;(node as Node).expand()
         }
       }
@@ -127,7 +136,7 @@ export default class TreeStore {
     refData: TreeKey | TreeNodeData | Node
   ): void {
     const refNode = this.getNode(refData)
-    refNode.parent.insertBefore({ data }, refNode)
+    refNode.parent?.insertBefore({ data }, refNode)
   }
 
   insertAfter(
@@ -135,7 +144,7 @@ export default class TreeStore {
     refData: TreeKey | TreeNodeData | Node
   ): void {
     const refNode = this.getNode(refData)
-    refNode.parent.insertAfter({ data }, refNode)
+    refNode.parent?.insertAfter({ data }, refNode)
   }
 
   remove(data: TreeNodeData | Node): void {
@@ -175,7 +184,7 @@ export default class TreeStore {
   _initDefaultCheckedNode(node: Node): void {
     const defaultCheckedKeys = this.defaultCheckedKeys || []
 
-    if (defaultCheckedKeys.includes(node.key)) {
+    if (!isNil(node.key) && defaultCheckedKeys.includes(node.key)) {
       node.setChecked(true, !this.checkStrictly)
     }
   }
@@ -195,7 +204,7 @@ export default class TreeStore {
       this.nodesMap[node.id] = node
     } else {
       const nodeKey = node.key
-      if (nodeKey !== undefined) this.nodesMap[node.key] = node
+      if (!isNil(nodeKey)) this.nodesMap[nodeKey] = node
     }
   }
 
@@ -207,7 +216,7 @@ export default class TreeStore {
       this.deregisterNode(child)
     })
 
-    delete this.nodesMap[node.key]
+    delete this.nodesMap[node.key!]
   }
 
   getCheckedNodes(
@@ -296,12 +305,12 @@ export default class TreeStore {
     key: TreeKey,
     leafOnly = false,
     checkedKeys: { [key: string]: boolean }
-  ): void {
+  ) {
     const allNodes = this._getAllNodes().sort((a, b) => a.level - b.level)
-    const cache = Object.create(null)
+    const cache: Record<TreeKey, boolean> = Object.create(null)
     const keys = Object.keys(checkedKeys)
     allNodes.forEach((node) => node.setChecked(false, false))
-    const cacheCheckedChild = (node) => {
+    const cacheCheckedChild = (node: Node) => {
       node.childNodes.forEach((child) => {
         cache[child.data[key]] = true
         if (child.childNodes?.length) {
@@ -311,7 +320,7 @@ export default class TreeStore {
     }
     for (let i = 0, j = allNodes.length; i < j; i++) {
       const node = allNodes[i]
-      const nodeKey = node.data[key].toString()
+      const nodeKey: string = node.data[key].toString()
       const checked = keys.includes(nodeKey)
       if (!checked) {
         if (node.checked && !cache[nodeKey]) {
@@ -348,9 +357,9 @@ export default class TreeStore {
 
   setCheckedNodes(array: Node[], leafOnly = false): void {
     const key = this.key
-    const checkedKeys = {}
+    const checkedKeys: Record<TreeKey, boolean> = {}
     array.forEach((item) => {
-      checkedKeys[(item || {})[key]] = true
+      checkedKeys[((item || {}) as any)[key]] = true
     })
 
     this._setCheckedKeys(key, leafOnly, checkedKeys)
@@ -359,7 +368,7 @@ export default class TreeStore {
   setCheckedKeys(keys: TreeKey[], leafOnly = false): void {
     this.defaultCheckedKeys = keys
     const key = this.key
-    const checkedKeys = {}
+    const checkedKeys: Record<TreeKey, boolean> = {}
     keys.forEach((key) => {
       checkedKeys[key] = true
     })
@@ -388,7 +397,7 @@ export default class TreeStore {
     }
   }
 
-  getCurrentNode(): Node {
+  getCurrentNode() {
     return this.currentNode
   }
 
@@ -402,15 +411,19 @@ export default class TreeStore {
   }
 
   setUserCurrentNode(node: Node, shouldAutoExpandParent = true): void {
-    const key = node[this.key]
+    const key = (node as any)[this.key]
     const currNode = this.nodesMap[key]
     this.setCurrentNode(currNode)
-    if (shouldAutoExpandParent && this.currentNode.level > 1) {
-      this.currentNode.parent.expand(null, true)
+    if (
+      shouldAutoExpandParent &&
+      this.currentNode &&
+      this.currentNode.level > 1
+    ) {
+      this.currentNode.parent?.expand(null, true)
     }
   }
 
-  setCurrentNodeKey(key?: TreeKey, shouldAutoExpandParent = true): void {
+  setCurrentNodeKey(key: TreeKey | null, shouldAutoExpandParent = true): void {
     this.currentNodeKey = key
     if (isPropAbsent(key)) {
       this.currentNode && (this.currentNode.isCurrent = false)
@@ -420,8 +433,12 @@ export default class TreeStore {
     const node = this.getNode(key)
     if (node) {
       this.setCurrentNode(node)
-      if (shouldAutoExpandParent && this.currentNode.level > 1) {
-        this.currentNode.parent.expand(null, true)
+      if (
+        shouldAutoExpandParent &&
+        this.currentNode &&
+        this.currentNode.level > 1
+      ) {
+        this.currentNode.parent?.expand(null, true)
       }
     }
   }
diff --git a/packages/components/tree/src/model/useDragNode.ts b/packages/components/tree/src/model/useDragNode.ts
index f70a66d6ff..6421eccdab 100644
--- a/packages/components/tree/src/model/useDragNode.ts
+++ b/packages/components/tree/src/model/useDragNode.ts
@@ -1,11 +1,16 @@
-// @ts-nocheck
 import { provide, ref } from 'vue'
 import { addClass, isFunction, removeClass } from '@element-plus/utils'
 import { useNamespace } from '@element-plus/hooks'
 
-import type { InjectionKey } from 'vue'
+import type { InjectionKey, Ref, SetupContext } from 'vue'
+import type {
+  AllowDragFunction,
+  AllowDropFunction,
+  FakeNode,
+  NodeDropType,
+} from '../tree.type'
+import type TreeStore from './tree-store'
 import type Node from './node'
-import type { NodeDropType } from '../tree.type'
 
 interface TreeNode {
   node: Node
@@ -17,6 +22,17 @@ interface DragOptions {
   treeNode: TreeNode
 }
 
+interface Props {
+  props: {
+    allowDrag?: AllowDragFunction
+    allowDrop?: AllowDropFunction
+  }
+  ctx: SetupContext<string[]>
+  el$: Ref<HTMLElement | null>
+  dropIndicator$: Ref<HTMLElement | null>
+  store: Ref<TreeStore>
+}
+
 export interface DragEvents {
   treeNodeDragStart: (options: DragOptions) => void
   treeNodeDragOver: (options: DragOptions) => void
@@ -25,9 +41,21 @@ export interface DragEvents {
 
 export const dragEventsKey: InjectionKey<DragEvents> = Symbol('dragEvents')
 
-export function useDragNodeHandler({ props, ctx, el$, dropIndicator$, store }) {
+export function useDragNodeHandler({
+  props,
+  ctx,
+  el$,
+  dropIndicator$,
+  store,
+}: Props) {
   const ns = useNamespace('tree')
-  const dragState = ref({
+  const dragState = ref<{
+    allowDrop: boolean
+    dropType: NodeDropType | null
+    draggingNode: TreeNode | null
+    showDropIndicator: boolean
+    dropNode: TreeNode | null
+  }>({
     showDropIndicator: false,
     draggingNode: null,
     dropNode: null,
@@ -36,6 +64,7 @@ export function useDragNodeHandler({ props, ctx, el$, dropIndicator$, store }) {
   })
 
   const treeNodeDragStart = ({ event, treeNode }: DragOptions) => {
+    if (!event.dataTransfer) return
     if (isFunction(props.allowDrag) && !props.allowDrag(treeNode.node)) {
       event.preventDefault()
       return false
@@ -53,10 +82,11 @@ export function useDragNodeHandler({ props, ctx, el$, dropIndicator$, store }) {
   }
 
   const treeNodeDragOver = ({ event, treeNode }: DragOptions) => {
+    if (!event.dataTransfer) return
     const dropNode = treeNode
     const oldDropNode = dragState.value.dropNode
     if (oldDropNode && oldDropNode.node.id !== dropNode.node.id) {
-      removeClass(oldDropNode.$el, ns.is('drop-inner'))
+      removeClass(oldDropNode.$el!, ns.is('drop-inner'))
     }
     const draggingNode = dragState.value.draggingNode
     if (!draggingNode || !dropNode) return
@@ -110,12 +140,13 @@ export function useDragNodeHandler({ props, ctx, el$, dropIndicator$, store }) {
       dropInner = false
       dropNext = false
     }
+    const dropEl = dropNode.$el!
 
     // find target node without children, just calc content node height
-    const targetPosition = dropNode.$el
-      .querySelector(`.${ns.be('node', 'content')}`)
+    const targetPosition = dropEl
+      .querySelector(`.${ns.be('node', 'content')}`)!
       .getBoundingClientRect()
-    const treePosition = el$.value.getBoundingClientRect()
+    const treePosition = el$.value!.getBoundingClientRect()
 
     let dropType: NodeDropType
     const prevPercent = dropPrev ? (dropInner ? 0.25 : dropNext ? 0.45 : 1) : -1
@@ -133,8 +164,8 @@ export function useDragNodeHandler({ props, ctx, el$, dropIndicator$, store }) {
       dropType = 'none'
     }
 
-    const iconPosition = dropNode.$el
-      .querySelector(`.${ns.be('node', 'expand-icon')}`)
+    const iconPosition = dropEl
+      .querySelector(`.${ns.be('node', 'expand-icon')}`)!
       .getBoundingClientRect()
     const dropIndicator = dropIndicator$.value
     if (dropType === 'before') {
@@ -142,13 +173,13 @@ export function useDragNodeHandler({ props, ctx, el$, dropIndicator$, store }) {
     } else if (dropType === 'after') {
       indicatorTop = iconPosition.bottom - treePosition.top
     }
-    dropIndicator.style.top = `${indicatorTop}px`
-    dropIndicator.style.left = `${iconPosition.right - treePosition.left}px`
+    dropIndicator!.style.top = `${indicatorTop}px`
+    dropIndicator!.style.left = `${iconPosition.right - treePosition.left}px`
 
     if (dropType === 'inner') {
-      addClass(dropNode.$el, ns.is('drop-inner'))
+      addClass(dropEl, ns.is('drop-inner'))
     } else {
-      removeClass(dropNode.$el, ns.is('drop-inner'))
+      removeClass(dropEl, ns.is('drop-inner'))
     }
 
     dragState.value.showDropIndicator =
@@ -168,20 +199,20 @@ export function useDragNodeHandler({ props, ctx, el$, dropIndicator$, store }) {
       event.dataTransfer.dropEffect = 'move'
     }
 
-    if (draggingNode && dropNode) {
-      const draggingNodeCopy = { data: draggingNode.node.data }
+    if (draggingNode?.node.data && dropNode) {
+      const draggingNodeCopy: FakeNode = { data: draggingNode.node.data }
       if (dropType !== 'none') {
         draggingNode.node.remove()
       }
       if (dropType === 'before') {
-        dropNode.node.parent.insertBefore(draggingNodeCopy, dropNode.node)
+        dropNode.node.parent?.insertBefore(draggingNodeCopy, dropNode.node)
       } else if (dropType === 'after') {
-        dropNode.node.parent.insertAfter(draggingNodeCopy, dropNode.node)
+        dropNode.node.parent?.insertAfter(draggingNodeCopy, dropNode.node)
       } else if (dropType === 'inner') {
         dropNode.node.insertChild(draggingNodeCopy)
       }
       if (dropType !== 'none') {
-        store.value.registerNode(draggingNodeCopy)
+        store.value.registerNode(draggingNodeCopy as any)
         if (store.value.key) {
           //restore checkbox state after dragging
           draggingNode.node.eachNode((node) => {
@@ -193,7 +224,7 @@ export function useDragNodeHandler({ props, ctx, el$, dropIndicator$, store }) {
         }
       }
 
-      removeClass(dropNode.$el, ns.is('drop-inner'))
+      removeClass(dropNode.$el!, ns.is('drop-inner'))
 
       ctx.emit(
         'node-drag-end',
diff --git a/packages/components/tree/src/model/useKeydown.ts b/packages/components/tree/src/model/useKeydown.ts
index 7353f5de76..bbd9be2dc5 100644
--- a/packages/components/tree/src/model/useKeydown.ts
+++ b/packages/components/tree/src/model/useKeydown.ts
@@ -1,4 +1,3 @@
-// @ts-nocheck
 import { onMounted, onUpdated } from 'vue'
 import { useEventListener } from '@vueuse/core'
 import { EVENT_CODE } from '@element-plus/constants'
@@ -9,7 +8,7 @@ import type { Ref } from 'vue'
 import type { Nullable } from '@element-plus/utils'
 
 interface UseKeydownOption {
-  el$: Ref<HTMLElement>
+  el$: Ref<HTMLElement | null>
 }
 export function useKeydown({ el$ }: UseKeydownOption, store: Ref<TreeStore>) {
   const ns = useNamespace('tree')
@@ -20,7 +19,7 @@ export function useKeydown({ el$ }: UseKeydownOption, store: Ref<TreeStore>) {
 
   onUpdated(() => {
     const checkboxItems = Array.from(
-      el$.value.querySelectorAll('input[type=checkbox]')
+      el$.value!.querySelectorAll('input[type=checkbox]')
     )
     checkboxItems.forEach((checkbox) => {
       checkbox.setAttribute('tabindex', '-1')
@@ -28,11 +27,11 @@ export function useKeydown({ el$ }: UseKeydownOption, store: Ref<TreeStore>) {
   })
 
   const handleKeydown = (ev: KeyboardEvent): void => {
-    const currentItem = ev.target as HTMLElement
+    const currentItem = ev.target as HTMLDivElement
     if (!currentItem.className.includes(ns.b('node'))) return
     const code = ev.code
-    const treeItems = Array.from(
-      el$.value.querySelectorAll(`.${ns.is('focusable')}[role=treeitem]`)
+    const treeItems: HTMLElement[] = Array.from(
+      el$.value!.querySelectorAll(`.${ns.is('focusable')}[role=treeitem]`)
     )
     const currentIndex = treeItems.indexOf(currentItem)
     let nextIndex
@@ -47,7 +46,7 @@ export function useKeydown({ el$ }: UseKeydownOption, store: Ref<TreeStore>) {
             : treeItems.length - 1
         const startIndex = nextIndex
         while (true) {
-          if (store.value.getNode(treeItems[nextIndex].dataset.key).canFocus)
+          if (store.value.getNode(treeItems[nextIndex].dataset.key!).canFocus)
             break
           nextIndex--
           if (nextIndex === startIndex) {
@@ -67,7 +66,7 @@ export function useKeydown({ el$ }: UseKeydownOption, store: Ref<TreeStore>) {
             : 0
         const startIndex = nextIndex
         while (true) {
-          if (store.value.getNode(treeItems[nextIndex].dataset.key).canFocus)
+          if (store.value.getNode(treeItems[nextIndex].dataset.key!).canFocus)
             break
           nextIndex++
           if (nextIndex === startIndex) {
@@ -102,6 +101,7 @@ export function useKeydown({ el$ }: UseKeydownOption, store: Ref<TreeStore>) {
   useEventListener(el$, 'keydown', handleKeydown)
 
   const initTabIndex = (): void => {
+    if (!el$.value) return
     const treeItems = Array.from(
       el$.value.querySelectorAll(`.${ns.is('focusable')}[role=treeitem]`)
     )
diff --git a/packages/components/tree/src/model/useNodeExpandEventBroadcast.ts b/packages/components/tree/src/model/useNodeExpandEventBroadcast.ts
index 879c5be79a..5a007352b3 100644
--- a/packages/components/tree/src/model/useNodeExpandEventBroadcast.ts
+++ b/packages/components/tree/src/model/useNodeExpandEventBroadcast.ts
@@ -1,20 +1,27 @@
-// @ts-nocheck
 import { inject, provide } from 'vue'
 import { TREE_NODE_MAP_INJECTION_KEY } from '../tokens'
 
 import type Node from '../model/node'
 
 interface NodeMap {
-  treeNodeExpand(node: Node): void
+  treeNodeExpand(node?: Node): void
   children: NodeMap[]
 }
 
-export function useNodeExpandEventBroadcast(props) {
-  const parentNodeMap = inject<NodeMap>(TREE_NODE_MAP_INJECTION_KEY, null)
+interface Props {
+  node?: Node
+  accordion: boolean
+}
+
+export function useNodeExpandEventBroadcast(props: Props) {
+  const parentNodeMap = inject(
+    TREE_NODE_MAP_INJECTION_KEY,
+    null
+  ) as NodeMap | null
   const currentNodeMap: NodeMap = {
     treeNodeExpand: (node) => {
       if (props.node !== node) {
-        props.node.collapse()
+        props.node?.collapse()
       }
     },
     children: [],
@@ -27,7 +34,7 @@ export function useNodeExpandEventBroadcast(props) {
   provide(TREE_NODE_MAP_INJECTION_KEY, currentNodeMap)
 
   return {
-    broadcastExpanded: (node: Node): void => {
+    broadcastExpanded: (node?: Node): void => {
       if (!props.accordion) return
       for (const childNode of currentNodeMap.children) {
         childNode.treeNodeExpand(node)
diff --git a/packages/components/tree/src/model/util.ts b/packages/components/tree/src/model/util.ts
index 7282ae3d2a..98aa74ae2f 100644
--- a/packages/components/tree/src/model/util.ts
+++ b/packages/components/tree/src/model/util.ts
@@ -4,7 +4,10 @@ import type { RootTreeType, TreeKey, TreeNodeData } from '../tree.type'
 
 export const NODE_KEY = '$treeNodeId'
 
-export const markNodeData = function (node: Node, data: TreeNodeData): void {
+export const markNodeData = function (
+  node: Node,
+  data: TreeNodeData | null
+): void {
   if (!data || data[NODE_KEY]) return
   Object.defineProperty(data, NODE_KEY, {
     value: node.id,
@@ -14,7 +17,7 @@ export const markNodeData = function (node: Node, data: TreeNodeData): void {
   })
 }
 
-export const getNodeKey = (key: TreeKey, data: TreeNodeData) =>
+export const getNodeKey = (key: TreeKey | undefined, data: TreeNodeData) =>
   data?.[key || NODE_KEY]
 
 export const handleCurrentChange = (
diff --git a/packages/components/tree/src/tree.type.ts b/packages/components/tree/src/tree.type.ts
index b09c079372..7b56d695f3 100644
--- a/packages/components/tree/src/tree.type.ts
+++ b/packages/components/tree/src/tree.type.ts
@@ -43,19 +43,19 @@ export interface TreeStoreNodesMap {
   [key: string]: Node
 }
 export interface TreeStoreOptions {
-  key: TreeKey
+  key?: TreeKey
   data: TreeData
   lazy: boolean
   props: TreeOptionProps
-  load: LoadFunction
-  currentNodeKey: TreeKey
+  load?: LoadFunction
+  currentNodeKey?: TreeKey
   checkStrictly: boolean
   checkDescendants: boolean
-  defaultCheckedKeys: TreeKey[]
-  defaultExpandedKeys: TreeKey[]
+  defaultCheckedKeys?: TreeKey[]
+  defaultExpandedKeys?: TreeKey[]
   autoExpandParent: boolean
   defaultExpandAll: boolean
-  filterNodeMethod: FilterNodeMethodFunction
+  filterNodeMethod?: FilterNodeMethodFunction
 }
 export interface TreeOptionProps {
   children?: string
diff --git a/packages/components/tree/src/tree.vue b/packages/components/tree/src/tree.vue
index 2716b62709..fbc44c7ad0 100644
--- a/packages/components/tree/src/tree.vue
+++ b/packages/components/tree/src/tree.vue
@@ -37,7 +37,6 @@
 </template>
 
 <script lang="ts">
-// @ts-nocheck
 import {
   computed,
   defineComponent,
@@ -47,7 +46,7 @@ import {
   ref,
   watch,
 } from 'vue'
-import { iconPropType } from '@element-plus/utils'
+import { definePropType, iconPropType } from '@element-plus/utils'
 import { useLocale, useNamespace } from '@element-plus/hooks'
 import { formItemContextKey } from '@element-plus/components/form'
 import { selectKey } from '@element-plus/components/select/src/token'
@@ -63,6 +62,10 @@ import type Node from './model/node'
 import type { ComponentInternalInstance, PropType } from 'vue'
 import type { Nullable } from '@element-plus/utils'
 import type {
+  AllowDragFunction,
+  AllowDropFunction,
+  FilterValue,
+  RenderContentFunction,
   TreeComponentProps,
   TreeData,
   TreeKey,
@@ -74,7 +77,7 @@ export default defineComponent({
   components: { ElTreeNode },
   props: {
     data: {
-      type: Array,
+      type: definePropType<TreeData>(Array),
       default: () => [],
     },
     emptyText: {
@@ -111,7 +114,9 @@ export default defineComponent({
       TreeComponentProps['defaultExpandedKeys']
     >,
     currentNodeKey: [String, Number] as PropType<string | number>,
-    renderContent: Function,
+    renderContent: {
+      type: definePropType<RenderContentFunction>(Function),
+    },
     showCheckbox: {
       type: Boolean,
       default: false,
@@ -120,8 +125,12 @@ export default defineComponent({
       type: Boolean,
       default: false,
     },
-    allowDrag: Function,
-    allowDrop: Function,
+    allowDrag: {
+      type: definePropType<AllowDragFunction>(Function),
+    },
+    allowDrop: {
+      type: definePropType<AllowDropFunction>(Function),
+    },
     props: {
       type: Object as PropType<TreeComponentProps['props']>,
       default: () => ({
@@ -162,7 +171,7 @@ export default defineComponent({
     'node-drag-leave',
     'node-drag-enter',
     'node-drag-over',
-  ],
+  ] as string[],
   setup(props, ctx) {
     const { t } = useLocale()
     const ns = useNamespace('tree')
@@ -189,7 +198,7 @@ export default defineComponent({
     store.value.initialize()
 
     const root = ref<Node>(store.value.root)
-    const currentNode = ref<Node>(null)
+    const currentNode = ref<Node | null>(null)
     const el$ = ref<Nullable<HTMLElement>>(null)
     const dropIndicator$ = ref<Nullable<HTMLElement>>(null)
 
@@ -208,7 +217,7 @@ export default defineComponent({
     const isEmpty = computed(() => {
       const { childNodes } = root.value
       const hasFilteredOptions = selectInfo
-        ? selectInfo.hasFilteredOptions !== 0
+        ? (selectInfo as any).hasFilteredOptions !== 0
         : false
       return (
         (!childNodes ||
@@ -221,21 +230,21 @@ export default defineComponent({
     watch(
       () => props.currentNodeKey,
       (newVal) => {
-        store.value.setCurrentNodeKey(newVal)
+        store.value.setCurrentNodeKey(newVal ?? null)
       }
     )
 
     watch(
       () => props.defaultCheckedKeys,
       (newVal) => {
-        store.value.setDefaultCheckedKey(newVal)
+        store.value.setDefaultCheckedKey(newVal ?? [])
       }
     )
 
     watch(
       () => props.defaultExpandedKeys,
       (newVal) => {
-        store.value.setDefaultExpandedKeys(newVal)
+        store.value.setDefaultExpandedKeys(newVal ?? [])
       }
     )
 
@@ -254,7 +263,7 @@ export default defineComponent({
       }
     )
 
-    const filter = (value) => {
+    const filter = (value: FilterValue) => {
       if (!props.filterNodeMethod)
         throw new Error('[Tree] filterNodeMethod is required when filter')
       store.value.filter(value)
@@ -289,12 +298,12 @@ export default defineComponent({
       return store.value.getCheckedKeys(leafOnly)
     }
 
-    const getCurrentNode = (): TreeNodeData => {
+    const getCurrentNode = () => {
       const currentNode = store.value.getCurrentNode()
       return currentNode ? currentNode.data : null
     }
 
-    const getCurrentKey = (): any => {
+    const getCurrentKey = (): TreeKey | null => {
       if (!props.nodeKey)
         throw new Error('[Tree] nodeKey is required in getCurrentKey')
       const currentNode = getCurrentNode()
@@ -345,7 +354,7 @@ export default defineComponent({
 
       handleCurrentChange(store, ctx.emit, () => {
         broadcastExpanded()
-        store.value.setCurrentNodeKey(key, shouldAutoExpandParent)
+        store.value.setCurrentNodeKey(key ?? null, shouldAutoExpandParent)
       })
     }
 
@@ -400,7 +409,7 @@ export default defineComponent({
       root,
       currentNode,
       instance: getCurrentInstance(),
-    } as any)
+    })
 
     provide(formItemContextKey, undefined)