diff --git a/problems/0617.合并二叉树.md b/problems/0617.合并二叉树.md
index 18839a26..9efeb56d 100644
--- a/problems/0617.合并二叉树.md
+++ b/problems/0617.合并二叉树.md
@@ -788,6 +788,20 @@ impl Solution {
     }
 }
 ```
+### C#
+```C#
+public TreeNode MergeTrees(TreeNode root1, TreeNode root2)
+{
+    if (root1 == null) return root2;
+    if (root2 == null) return root1;
+
+    root1.val += root2.val;
+    root1.left = MergeTrees(root1.left, root2.left);
+    root1.right = MergeTrees(root1.right, root2.right);
+
+    return root1;
+}
+```
 
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