diff --git a/docs/cs-basics/data-structure/tree.md b/docs/cs-basics/data-structure/tree.md
index eb9d9964..6b016ce5 100644
--- a/docs/cs-basics/data-structure/tree.md
+++ b/docs/cs-basics/data-structure/tree.md
@@ -176,8 +176,8 @@ public void postOrder(TreeNode root){
 	if(root == null){
 		return;
 	}
-	postOrder(root.left);
 	postOrder(root.right);
+	postOrder(root.left);
 	system.out.println(root.data);
 }
 ```