diff --git a/problems/0216.组合总和III.md b/problems/0216.组合总和III.md
index c0cb8860..ac28f9fc 100644
--- a/problems/0216.组合总和III.md
+++ b/problems/0216.组合总和III.md
@@ -633,7 +633,66 @@ object Solution {
   }
 }
 ```
-
+### C#
+```csharp
+public class Solution
+{
+    public IList<IList<int>> res = new List<IList<int>>();
+    public IList<int> path = new List<int>();
+    public IList<IList<int>> CombinationSum3(int k, int n)
+    {
+        BackTracking(k, n, 0, 1);
+        return res;
+    }
+    public void BackTracking(int k, int n, int sum, int start)
+    {
+        if (path.Count == k)
+        {
+            if (sum == n)
+                res.Add(new List<int>(path));
+            return;
+        }
+        for (int i = start; i <= 9; i++)
+        {
+            sum += i;
+            path.Add(i);
+            BackTracking(k, n, sum, i + 1);
+            sum -= i;
+            path.RemoveAt(path.Count - 1);
+        }
+    }
+}
+// 剪枝
+public class Solution
+{
+    public IList<IList<int>> res = new List<IList<int>>();
+    public IList<int> path = new List<int>();
+    public IList<IList<int>> CombinationSum3(int k, int n)
+    {
+        BackTracking(k, n, 0, 1);
+        return res;
+    }
+    public void BackTracking(int k, int n, int sum, int start)
+    {
+        if (sum > n)
+            return;
+        if (path.Count == k)
+        {
+            if (sum == n)
+                res.Add(new List<int>(path));
+            return;
+        }
+        for (int i = start; i <= 9 - (k - path.Count) + 1; i++)
+        {
+            sum += i;
+            path.Add(i);
+            BackTracking(k, n, sum, i + 1);
+            sum -= i;
+            path.RemoveAt(path.Count - 1);
+        }
+    }
+}
+```