diff --git a/notes/28. 对称的二叉树.md b/notes/28. 对称的二叉树.md
index 15181506..bf955019 100644
--- a/notes/28. 对称的二叉树.md
+++ b/notes/28. 对称的二叉树.md
@@ -4,7 +4,9 @@
## 题目描述
-
+判断一棵二叉树是不是对称的，也就是它和它的镜像是否相同。
+
+
## 解题思路
diff --git a/notes/pics/offer28-symmetric-tree.png b/notes/pics/offer28-symmetric-tree.png
new file mode 100644
index 00000000..cc43f252
Binary files /dev/null and b/notes/pics/offer28-symmetric-tree.png differ
