diff --git a/.env.example b/.env.example
index a211b2a..2f636e0 100644
--- a/.env.example
+++ b/.env.example
@@ -9,8 +9,9 @@
 DATA_DIR=
 
 # Set Templates
-# Specifies the template set to use for prompts.
+# Specifies the template set to use for prompts and WebGUI language.
 # Default is 'en'. Currently available options are 'en' and 'zh'.
+# When using custom templates, WebGUI will default to English interface.
 # To use custom templates, copy the 'src/prompts/templates_en' directory
 # to the location specified by DATA_DIR, rename the copied directory
 # (e.g., to 'my_templates'), and set TEMPLATES_USE to the new directory name (e.g., 'my_templates').
diff --git a/src/index.ts b/src/index.ts
index ebf908c..bf37eb7 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -147,9 +147,19 @@ async function main() {
         } catch (watchError) {}
       });
 
-      // 將 URL 寫入 ebGUI.md
+      // 將 URL 寫入 WebGUI.md
       try {
-        const websiteUrl = `[Task Manager UI](http://localhost:${port})`;
+        // 讀取 TEMPLATES_USE 環境變數並轉換為語言代碼
+        const templatesUse = process.env.TEMPLATES_USE || "en";
+        const getLanguageFromTemplate = (template: string): string => {
+          if (template === "zh") return "zh-TW";
+          if (template === "en") return "en";
+          // 自訂範本預設使用英文
+          return "en";
+        };
+        const language = getLanguageFromTemplate(templatesUse);
+
+        const websiteUrl = `[Task Manager UI](http://localhost:${port}?lang=${language})`;
         const websiteFilePath = path.join(DATA_DIR, "WebGUI.md");
         await fsPromises.writeFile(websiteFilePath, websiteUrl, "utf-8");
       } catch (error) {}
diff --git a/src/public/script.js b/src/public/script.js
index 4f4a90e..ec2b816 100644
--- a/src/public/script.js
+++ b/src/public/script.js
@@ -69,21 +69,25 @@ document.addEventListener("DOMContentLoaded", () => {
 });
 
 // 新增：i18n 核心函數
-// 1. 語言檢測 (localStorage > navigator.language > 'en')
+// 1. 語言檢測 (URL 參數 > navigator.language > 'en')
 function detectLanguage() {
-  const savedLang = localStorage.getItem("lang");
-  if (savedLang && ["en", "zh-TW"].includes(savedLang)) {
-    // 確保保存的是有效語言
-    return savedLang;
+  // 1. 優先從 URL 參數讀取
+  const urlParams = new URLSearchParams(window.location.search);
+  const urlLang = urlParams.get("lang");
+  if (urlLang && ["en", "zh-TW"].includes(urlLang)) {
+    return urlLang;
   }
-  // 檢查瀏覽器語言
+
+  // 2. 檢查瀏覽器語言（移除 localStorage 檢查）
   const browserLang = navigator.language || navigator.userLanguage;
   if (browserLang) {
     if (browserLang.toLowerCase().startsWith("zh-tw")) return "zh-TW";
     if (browserLang.toLowerCase().startsWith("zh")) return "zh-TW"; // 簡體也先 fallback 到繁體
     if (browserLang.toLowerCase().startsWith("en")) return "en";
   }
-  return "en"; // 預設
+
+  // 3. 預設值
+  return "en";
 }
 
 // 2. 異步加載翻譯文件
@@ -152,7 +156,6 @@ function applyTranslations() {
 async function initI18n() {
   currentLang = detectLanguage();
   console.log(`Initializing i18n with language: ${currentLang}`);
-  localStorage.setItem("lang", currentLang); // 確保 lang 被保存
   // << 新增：設置切換器的初始值 >>
   if (langSwitcher) {
     langSwitcher.value = currentLang;
@@ -169,7 +172,6 @@ function changeLanguage(lang) {
     lang = "en";
   }
   currentLang = lang;
-  localStorage.setItem("lang", lang);
   console.log(`Changing language to: ${currentLang}`);
   loadTranslations(currentLang)
     .then(() => {