diff --git a/app/Listeners/SetAppLocale.php b/app/Listeners/SetAppLocale.php
new file mode 100644
index 00000000..e4e4688e
--- /dev/null
+++ b/app/Listeners/SetAppLocale.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Listeners;
+
+use App\Models\User;
+use Illuminate\Http\Request;
+
+class SetAppLocale
+{
+    /** @var Request */
+    protected $request;
+
+    public function __construct(Request $request)
+    {
+        $this->request = $request;
+    }
+
+    public function handle($event)
+    {
+        /** @var User */
+        $user = $event->user;
+
+        if ($this->request->has('lang')) {
+            $user->locale = $this->request->input('lang');
+            $user->save();
+
+            return;
+        }
+
+        $locale = $user->locale;
+        if ($locale) {
+            app()->setLocale($locale);
+        }
+    }
+}
diff --git a/app/Providers/EventServiceProvider.php b/app/Providers/EventServiceProvider.php
index 247401ee..94fcdf1b 100644
--- a/app/Providers/EventServiceProvider.php
+++ b/app/Providers/EventServiceProvider.php
@@ -33,5 +33,8 @@ class EventServiceProvider extends ServiceProvider
         'closet.removed' => [
             Listeners\ResetPlayerForRemovedClosetItem::class,
         ],
+        'Illuminate\Auth\Events\Authenticated' => [
+            Listeners\SetAppLocale::class,
+        ],
     ];
 }
diff --git a/database/factories/UserModelFactory.php b/database/factories/UserModelFactory.php
index 00239f0b..ef9fad36 100644
--- a/database/factories/UserModelFactory.php
+++ b/database/factories/UserModelFactory.php
@@ -8,6 +8,7 @@ $factory->define(User::class, function (Faker\Generator $faker) {
     return [
         'email' => $faker->email,
         'nickname' => $faker->name,
+        'locale' => null,
         'score' => 1000,
         'avatar' => 0,
         'password' => app('cipher')->hash(Str::random(10), config('secure.salt')),
diff --git a/tests/ListenersTest/SetAppLocaleTest.php b/tests/ListenersTest/SetAppLocaleTest.php
new file mode 100644
index 00000000..7bac0557
--- /dev/null
+++ b/tests/ListenersTest/SetAppLocaleTest.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Tests;
+
+use App\Models\User;
+use Illuminate\Foundation\Testing\DatabaseTransactions;
+
+class SetAppLocaleTest extends TestCase
+{
+    use DatabaseTransactions;
+
+    public function testUpdateUserLocale()
+    {
+        $user = factory(User::class)->create();
+
+        // This is a hacky way.
+        // We must call `get` first before set authentication,
+        // since this let Laravel update the `Request` instance,
+        // otherwise the event handler will be called first and
+        // it won't be able to retrieve request information.
+        $this->get('/?lang=en');
+        $this->actingAs($user);
+
+        $this->assertEquals('en', $user->fresh()->locale);
+    }
+
+    public function testSetAppLocale()
+    {
+        $user = factory(User::class)->create(['locale' => 'zh_CN']);
+
+        event(new \Illuminate\Auth\Events\Authenticated('web', $user));
+        $this->assertEquals('zh_CN', app()->getLocale());
+
+        app()->setLocale('en');
+    }
+}