diff --git a/solution/0400-0499/0409.Longest Palindrome/README.md b/solution/0400-0499/0409.Longest Palindrome/README.md
index 280e44f92119c..abb7f7858579f 100644
--- a/solution/0400-0499/0409.Longest Palindrome/README.md	
+++ b/solution/0400-0499/0409.Longest Palindrome/README.md	
@@ -70,6 +70,24 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function longestPalindrome(s: string): number {
+    let n = s.length;
+    let ans = 0;
+    let record = new Array(128).fill(0);
+    for (let i = 0; i < n; i++) {
+        record[s.charCodeAt(i)]++;
+    }
+    for (let i = 65; i < 128; i++) {
+        let count = record[i];
+        ans += (count % 2 == 0 ? count : count - 1);
+    }
+    return ans < s.length ? ans + 1 : ans;
+};
+```
+
 ### **...**
 
 ```
diff --git a/solution/0400-0499/0409.Longest Palindrome/README_EN.md b/solution/0400-0499/0409.Longest Palindrome/README_EN.md
index ae14d3d179e74..a8f844202d39d 100644
--- a/solution/0400-0499/0409.Longest Palindrome/README_EN.md	
+++ b/solution/0400-0499/0409.Longest Palindrome/README_EN.md	
@@ -78,6 +78,24 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function longestPalindrome(s: string): number {
+    let n = s.length;
+    let ans = 0;
+    let record = new Array(128).fill(0);
+    for (let i = 0; i < n; i++) {
+        record[s.charCodeAt(i)]++;
+    }
+    for (let i = 65; i < 128; i++) {
+        let count = record[i];
+        ans += (count % 2 == 0 ? count : count - 1);
+    }
+    return ans < s.length ? ans + 1 : ans;
+};
+```
+
 ### **...**
 
 ```
diff --git a/solution/0400-0499/0409.Longest Palindrome/Solution.ts b/solution/0400-0499/0409.Longest Palindrome/Solution.ts
new file mode 100644
index 0000000000000..991a886ffafe1
--- /dev/null
+++ b/solution/0400-0499/0409.Longest Palindrome/Solution.ts	
@@ -0,0 +1,13 @@
+function longestPalindrome(s: string): number {
+    let n = s.length;
+    let ans = 0;
+    let record = new Array(128).fill(0);
+    for (let i = 0; i < n; i++) {
+        record[s.charCodeAt(i)]++;
+    }
+    for (let i = 65; i < 128; i++) {
+        let count = record[i];
+        ans += (count % 2 == 0 ? count : count - 1);
+    }
+    return ans < s.length ? ans + 1 : ans;
+};
\ No newline at end of file