diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md
index fb92b1e4..1338cd0d 100644
--- a/problems/0541.反转字符串II.md
+++ b/problems/0541.反转字符串II.md
@@ -272,9 +272,21 @@ func reverseStr(_ s: String, _ k: Int) -> String {
 }
 ```
 
-
-
-
+C#：
+```csharp
+public class Solution
+{
+    public string ReverseStr(string s, int k)
+    {
+        Span<char> span = s.ToCharArray().AsSpan();
+        for (int i = 0; i < span.Length; i += 2 * k)
+        {
+            span[i + k < span.Length ? i..(i + k) : i..].Reverse();
+        }
+        return span.ToString();
+    }
+}
+```
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>