diff --git a/problems/0669.修剪二叉搜索树.md b/problems/0669.修剪二叉搜索树.md
index 442ea8fb..8b9e1f6d 100644
--- a/problems/0669.修剪二叉搜索树.md
+++ b/problems/0669.修剪二叉搜索树.md
@@ -242,25 +242,22 @@ public:
 
 
 Java：
-```java
+
+```Java
 class Solution {
     public TreeNode trimBST(TreeNode root, int low, int high) {
-        root = trim(root,low,high);
-        return root;
-    }
-
-    private static TreeNode trim(TreeNode root,int low, int high) {
-        if (root == null ) return null;
+        if (root == null) {
+            return null;
+        }
         if (root.val < low) {
-            return trim(root.right,low,high);
+            return trimBST(root.right, low, high);
         }
         if (root.val > high) {
-            return trim(root.left,low,high);
+            return trimBST(root.left, low, high);
         }
-
-        root.left = trim(root.left,low,high);
-        root.right = trim(root.right,low,high);
-
+        // root在[low,high]范围内
+        root.left = trimBST(root.left, low, high);
+        root.right = trimBST(root.right, low, high);
         return root;
     }
 }