diff --git a/docs/chapter_tree/binary_tree.md b/docs/chapter_tree/binary_tree.md
index f83ebee37..f13bfcb55 100644
--- a/docs/chapter_tree/binary_tree.md
+++ b/docs/chapter_tree/binary_tree.md
@@ -493,6 +493,8 @@
     P->left = n2;
     // 删除节点 P
     n1->left = n2;
+    // 释放内存
+    delete P;
     ```
 
 === "Java"
@@ -598,6 +600,8 @@
     P->left = n2;
     // 删除节点 P
     n1->left = n2;
+    // 释放内存
+    free(P);
     ```
 
 === "Kotlin"