diff --git a/website/package.json b/website/package.json
index 3ce195fce69..62d3fd787b9 100644
--- a/website/package.json
+++ b/website/package.json
@@ -11,7 +11,8 @@
     "dev": "npm run generate && npm run clean && next dev",
     "build": "npm run generate && npm run clean && next build",
     "postbuild": "node scripts/set-html-lang.js && pagefind --site out --output-path out/_pagefind --exclude-selectors 'noscript,script,style,pre,code,.nextra-code-block,.nextra-toc,.nextra-sidebar,.nextra-breadcrumb,.nextra-banner'",
-    "preview": "node scripts/preview.js"
+    "preview": "node scripts/preview.js",
+    "test": "tsx --test src/**/*.test.ts"
   },
   "keywords": [
     "qwen",
diff --git a/website/src/components/custom-navbar.tsx b/website/src/components/custom-navbar.tsx
index 0265b306848..4889792dea6 100644
--- a/website/src/components/custom-navbar.tsx
+++ b/website/src/components/custom-navbar.tsx
@@ -9,6 +9,8 @@ import { Button } from "nextra/components";
 import { FileText, Star, BookOpen, Newspaper } from "lucide-react";
 import { ThemeToggle } from "./theme-toggle";
 import { get } from "http";
+import { getBasePath } from "@/lib/blog-utils";
+import { getLocaleFromPathname } from "@/lib/locale-path";
 
 // 定义接口类型
 interface NavbarProps {
@@ -76,16 +78,11 @@ const getUserLanguage = (): string => {
   if (typeof window === "undefined") return "en";
 
   // 首先从URL路径中获取语言
-  const pathname = window.location.pathname;
-  const pathSegments = pathname.split("/").filter(Boolean);
-
-  if (pathSegments.length > 0) {
-    const possibleLang = pathSegments[0];
-    const supportedLanguages = ["en", "zh", "de", "fr", "ru", "ja", "pt-BR"];
-    if (supportedLanguages.includes(possibleLang)) {
-      return possibleLang;
-    }
-  }
+  const pathLocale = getLocaleFromPathname(
+    window.location.pathname,
+    getBasePath()
+  );
+  if (pathLocale) return pathLocale;
 
   // 如果URL中没有语言信息，使用浏览器语言
   const browserLang = navigator.language.toLowerCase();
diff --git a/website/src/lib/locale-path.test.ts b/website/src/lib/locale-path.test.ts
new file mode 100644
index 00000000000..1901aa5d12c
--- /dev/null
+++ b/website/src/lib/locale-path.test.ts
@@ -0,0 +1,23 @@
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+import { getLocaleFromPathname } from "./locale-path";
+
+describe("getLocaleFromPathname", () => {
+  it("finds a locale after the production base path", () => {
+    assert.equal(
+      getLocaleFromPathname(
+        "/qwen-code-docs/fr/users/overview/",
+        "/qwen-code-docs"
+      ),
+      "fr"
+    );
+  });
+
+  it("finds a locale when the site runs without a base path", () => {
+    assert.equal(getLocaleFromPathname("/pt-BR/blog/"), "pt-BR");
+  });
+
+  it("returns undefined when the path has no supported locale", () => {
+    assert.equal(getLocaleFromPathname("/qwen-code-docs/"), undefined);
+  });
+});
diff --git a/website/src/lib/locale-path.ts b/website/src/lib/locale-path.ts
new file mode 100644
index 00000000000..6cf33cb6454
--- /dev/null
+++ b/website/src/lib/locale-path.ts
@@ -0,0 +1,25 @@
+const SUPPORTED_LOCALES = [
+  "en",
+  "zh",
+  "de",
+  "fr",
+  "ru",
+  "ja",
+  "pt-BR",
+] as const;
+
+export type SupportedLocale = (typeof SUPPORTED_LOCALES)[number];
+
+/** Returns the route locale after removing an optional deployment base path. */
+export function getLocaleFromPathname(
+  pathname: string,
+  basePath = ""
+): SupportedLocale | undefined {
+  const routePath =
+    basePath && (pathname === basePath || pathname.startsWith(`${basePath}/`))
+      ? pathname.slice(basePath.length)
+      : pathname;
+  const locale = routePath.split("/").find(Boolean);
+
+  return SUPPORTED_LOCALES.find((supported) => supported === locale);
+}