diff --git a/problems/0701.二叉搜索树中的插入操作.md b/problems/0701.二叉搜索树中的插入操作.md
index 61027453..1ec80da1 100644
--- a/problems/0701.二叉搜索树中的插入操作.md
+++ b/problems/0701.二叉搜索树中的插入操作.md
@@ -255,7 +255,7 @@ class Solution {
 
 Python：
 
-递归法
+**递归法** - 有返回值
 
 ```python
 class Solution:
@@ -268,7 +268,63 @@ class Solution:
             root.left = self.insertIntoBST(root.left, val) # 递归创建左子树
         return root
 ```
+**递归法** - 无返回值
+```python
+class Solution:
+    def insertIntoBST(self, root: TreeNode, val: int) -> TreeNode:
+        if not root: 
+            return TreeNode(val)
+        parent = None
+        def __traverse(cur: TreeNode, val: int) -> None: 
+            # 在函数运行的同时把新节点插入到该被插入的地方. 
+            nonlocal parent
+            if not cur: 
+                new_node = TreeNode(val)
+                if parent.val < val: 
+                    parent.right = new_node
+                else: 
+                    parent.left = new_node
+                return 
 
+            parent = cur # 重点: parent的作用只有运行到上面if not cur:才会发挥出来.
+            if cur.val < val: 
+                __traverse(cur.right, val)
+            else: 
+                __traverse(cur.left, val)
+            return
+        __traverse(root, val)
+        return root
+```
+**迭代法**  
+与无返回值的递归函数的思路大体一致 
+```python
+class Solution:
+    def insertIntoBST(self, root: TreeNode, val: int) -> TreeNode:
+        if not root: 
+            return TreeNode(val)
+        parent = None
+        cur = root
+
+        # 用while循环不断地找新节点的parent
+        while cur: 
+            if cur.val < val: 
+                parent = cur
+                cur = cur.right
+            elif cur.val > val: 
+                parent = cur
+                cur = cur.left
+
+        # 运行到这意味着已经跳出上面的while循环, 
+        # 同时意味着新节点的parent已经被找到.
+        # parent已被找到, 新节点已经ready. 把两个节点黏在一起就好了. 
+        if parent.val > val: 
+            parent.left = TreeNode(val)
+        else: 
+            parent.right = TreeNode(val)
+        
+        return root
+            
+```
 
 Go：