diff --git a/src/components/admin/toolbar.tsx b/src/components/admin/toolbar.tsx
index 6f76f31..13611e3 100644
--- a/src/components/admin/toolbar.tsx
+++ b/src/components/admin/toolbar.tsx
@@ -2,11 +2,14 @@
 
 import {
   BellIcon,
+  CheckIcon,
   ChevronDownIcon,
+  GlobeIcon,
   LogOutIcon,
   UserRoundIcon,
 } from "lucide-react";
 import { useRouter } from "next/navigation";
+import { useEffect, useState } from "react";
 import { toast } from "sonner";
 
 import { Avatar, AvatarFallback } from "@/components/ui/avatar";
@@ -21,6 +24,13 @@ import {
   DropdownMenuTrigger,
 } from "@/components/ui/dropdown-menu";
 import { Separator } from "@/components/ui/separator";
+import {
+  ADMIN_API_LOCALES,
+  ADMIN_LOCALE_LABELS,
+  applyAdminUiLocale,
+  getAdminRequestLocale,
+  type AdminApiLocale,
+} from "@/lib/admin-locale";
 import {
   useAdminProfile,
   useAdminSessionStore,
@@ -68,6 +78,17 @@ export function ShellToolbar() {
   const router = useRouter();
   const adminProfile = useAdminProfile();
   const clearSession = useAdminSessionStore((s) => s.clearSession);
+  const [locale, setLocale] = useState<AdminApiLocale>(() =>
+    typeof document !== "undefined"
+      ? getAdminRequestLocale()
+      : "zh",
+  );
+
+  useEffect(() => {
+    queueMicrotask(() => {
+      setLocale(getAdminRequestLocale());
+    });
+  }, []);
 
   const displayName =
     adminProfile?.nickname?.trim() ||
@@ -81,6 +102,13 @@ export function ShellToolbar() {
     router.refresh();
   }
 
+  function onSelectLocale(next: AdminApiLocale) {
+    applyAdminUiLocale(next);
+    setLocale(next);
+    toast.success(`语言：${ADMIN_LOCALE_LABELS[next]}`);
+    router.refresh();
+  }
+
   return (
     <div className="flex items-center gap-2 sm:gap-3">
       <Button
@@ -102,6 +130,39 @@ export function ShellToolbar() {
 
       <Separator orientation="vertical" className="mx-0.5 h-7" />
 
+      <DropdownMenu>
+        <DropdownMenuTrigger className="inline-flex size-8 shrink-0 items-center justify-center rounded-lg text-muted-foreground outline-none hover:bg-muted hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring">
+          <GlobeIcon className="size-5 stroke-[1.75]" aria-hidden />
+          <span className="sr-only">语言</span>
+        </DropdownMenuTrigger>
+        <DropdownMenuContent align="end" className="min-w-[10rem]">
+          <DropdownMenuGroup>
+            <DropdownMenuLabel className="text-xs text-muted-foreground">
+              界面语言 / Language
+            </DropdownMenuLabel>
+            {ADMIN_API_LOCALES.map((code) => (
+              <DropdownMenuItem
+                key={code}
+                className="gap-2"
+                onClick={() => onSelectLocale(code)}
+              >
+                {locale === code ? (
+                  <CheckIcon className="size-4 opacity-100" />
+                ) : (
+                  <span className="size-4 shrink-0" aria-hidden />
+                )}
+                <span className="flex-1">{ADMIN_LOCALE_LABELS[code]}</span>
+                <span className="text-xs text-muted-foreground uppercase">
+                  {code}
+                </span>
+              </DropdownMenuItem>
+            ))}
+          </DropdownMenuGroup>
+        </DropdownMenuContent>
+      </DropdownMenu>
+
+      <Separator orientation="vertical" className="mx-0.5 h-7" />
+
       <DropdownMenu>
         <DropdownMenuTrigger className="flex max-w-[min(100vw-8rem,14rem)] items-center gap-2 rounded-lg px-1.5 py-1 text-left outline-none hover:bg-muted/80 focus-visible:ring-2 focus-visible:ring-ring sm:max-w-[16rem]">
           <Avatar size="sm" className="ring-1 ring-border">
diff --git a/src/components/providers.tsx b/src/components/providers.tsx
index b922f56..7d9841b 100644
--- a/src/components/providers.tsx
+++ b/src/components/providers.tsx
@@ -6,6 +6,7 @@ import { ThemeProvider } from "next-themes";
 
 import { Toaster } from "@/components/ui/sonner";
 import { TooltipProvider } from "@/components/ui/tooltip";
+import { hydrateAdminUiLocale } from "@/lib/admin-locale";
 import { useAdminSessionStore } from "@/stores/admin-session";
 
 type ProvidersProps = {
@@ -14,6 +15,7 @@ type ProvidersProps = {
 
 function AdminSessionHydrator() {
   useEffect(() => {
+    hydrateAdminUiLocale();
     useAdminSessionStore.getState().rehydrate();
   }, []);
 
diff --git a/src/lib/admin-http.ts b/src/lib/admin-http.ts
index 0ecb57f..e17e621 100644
--- a/src/lib/admin-http.ts
+++ b/src/lib/admin-http.ts
@@ -5,6 +5,7 @@ import axios, {
 } from "axios";
 
 import { withAdminAuthHeader } from "@/lib/admin-auth";
+import { withAdminLocaleHeaders } from "@/lib/admin-locale";
 import { LotteryApiBizError, LotteryApiEnvelopeError } from "@/types/api/errors";
 import { isApiEnvelope } from "@/types/api/envelope";
 
@@ -40,7 +41,9 @@ export async function publicAdminRequest<T>(
   config: AxiosRequestConfig,
 ): Promise<T> {
   try {
-    const res = await adminHttp.request<unknown>(config);
+    const res = await adminHttp.request<unknown>(
+      withAdminLocaleHeaders(config),
+    );
     return unwrapResponse<T>(res);
   } catch (err: unknown) {
     if (isAxiosError(err) && err.response?.data !== undefined) {
@@ -54,7 +57,7 @@ export async function publicAdminRequest<T>(
 }
 
 export async function request<T>(config: AxiosRequestConfig): Promise<T> {
-  const merged = withAdminAuthHeader(config);
+  const merged = withAdminAuthHeader(withAdminLocaleHeaders(config));
   try {
     const res = await adminHttp.request<unknown>(merged);
     return unwrapResponse<T>(res);
diff --git a/src/lib/admin-locale.ts b/src/lib/admin-locale.ts
new file mode 100644
index 0000000..bf598ef
--- /dev/null
+++ b/src/lib/admin-locale.ts
@@ -0,0 +1,127 @@
+import { AxiosHeaders, type AxiosRequestConfig } from "axios";
+
+/** 与 Laravel `NegotiateLotteryLocale`、`lottery.locales.supported`（zh/en/ne）一致 */
+export type AdminApiLocale = "zh" | "en" | "ne";
+
+export const ADMIN_API_LOCALES: readonly AdminApiLocale[] = ["zh", "en", "ne"];
+
+export const ADMIN_LOCALE_LABELS: Record<AdminApiLocale, string> = {
+  zh: "简体中文",
+  en: "English",
+  ne: "नेपाली",
+};
+
+const STORAGE_KEY = "lottery_admin_ui_locale";
+
+let overrideLocale: AdminApiLocale | null = null;
+
+function isApiLocale(value: string): value is AdminApiLocale {
+  return value === "zh" || value === "en" || value === "ne";
+}
+
+/** 覆盖后续 API 请求的 `X-Locale`（传 `null` 取消覆盖，改回 `document.documentElement.lang` / 默认） */
+export function setAdminRequestLocale(locale: string | null): void {
+  if (locale === null) {
+    overrideLocale = null;
+    return;
+  }
+  const p = locale.trim().toLowerCase().split("-")[0] ?? "";
+  overrideLocale = isApiLocale(p) ? p : null;
+}
+
+function requestLocale(): AdminApiLocale {
+  if (overrideLocale) {
+    return overrideLocale;
+  }
+  if (typeof document !== "undefined") {
+    const tag = document.documentElement.lang.trim().toLowerCase();
+    const primary = tag.split("-")[0] ?? tag;
+    if (isApiLocale(primary)) {
+      return primary;
+    }
+  }
+  return "en";
+}
+
+/** 当前生效的语言（与即将发出的 API 头一致） */
+export function getAdminRequestLocale(): AdminApiLocale {
+  return requestLocale();
+}
+
+function acceptLanguage(loc: AdminApiLocale): string {
+  if (loc === "zh") {
+    return "zh-CN,zh;q=0.9,en;q=0.8";
+  }
+  if (loc === "ne") {
+    return "ne,ne-NP;q=0.9,en;q=0.8";
+  }
+  return "en-US,en;q=0.9";
+}
+
+/** 与 `<html lang>` 对齐的 BCP 47 标签 */
+export function adminHtmlLang(loc: AdminApiLocale): string {
+  if (loc === "zh") {
+    return "zh-Hans";
+  }
+  if (loc === "ne") {
+    return "ne";
+  }
+  return "en";
+}
+
+function readStoredUiLocale(): AdminApiLocale | null {
+  if (typeof window === "undefined") {
+    return null;
+  }
+  const raw = window.localStorage.getItem(STORAGE_KEY)?.trim().toLowerCase();
+  if (raw && isApiLocale(raw)) {
+    return raw;
+  }
+
+  return null;
+}
+
+function writeStoredUiLocale(loc: AdminApiLocale): void {
+  if (typeof window === "undefined") {
+    return;
+  }
+  window.localStorage.setItem(STORAGE_KEY, loc);
+}
+
+/**
+ * 切换界面语言：写入 localStorage、同步 `document.documentElement.lang`、设置 API `X-Locale` 覆盖。
+ */
+export function applyAdminUiLocale(loc: AdminApiLocale): void {
+  setAdminRequestLocale(loc);
+  writeStoredUiLocale(loc);
+  if (typeof document !== "undefined") {
+    document.documentElement.lang = adminHtmlLang(loc);
+  }
+}
+
+/** 启动时从 localStorage 恢复（应在客户端尽早调用一次） */
+export function hydrateAdminUiLocale(): void {
+  if (typeof window === "undefined") {
+    return;
+  }
+  const stored = readStoredUiLocale();
+  if (stored) {
+    setAdminRequestLocale(stored);
+    document.documentElement.lang = adminHtmlLang(stored);
+  }
+}
+
+/** 供 `admin-http`：`X-Locale` + `Accept-Language` */
+export function withAdminLocaleHeaders(
+  config: AxiosRequestConfig,
+): AxiosRequestConfig {
+  const loc = requestLocale();
+  const merged: AxiosRequestConfig = { ...config };
+  const headers = AxiosHeaders.concat(
+    merged.headers as Parameters<typeof AxiosHeaders.concat>[0],
+  );
+  headers.set("X-Locale", loc);
+  headers.set("Accept-Language", acceptLanguage(loc));
+  merged.headers = headers;
+  return merged;
+}