diff --git a/flutter/lib/cm_main.dart b/flutter/lib/cm_main.dart
index bf72849e8..a92edd194 100644
--- a/flutter/lib/cm_main.dart
+++ b/flutter/lib/cm_main.dart
@@ -25,6 +25,6 @@ void main(List<String> args) async {
       .add(Client(3, false, false, "UserD", "441123123", true, false, false));
   runApp(GetMaterialApp(
       debugShowCheckedModeBanner: false,
-      theme: getCurrentTheme(),
+      theme: MyTheme.initialTheme(),
       home: DesktopServerPage()));
 }
diff --git a/flutter/lib/common.dart b/flutter/lib/common.dart
index da644c357..bd16fa4c5 100644
--- a/flutter/lib/common.dart
+++ b/flutter/lib/common.dart
@@ -192,6 +192,28 @@ class MyTheme {
     ],
   );
 
+  static changeTo(bool dark) {
+    Get.find<SharedPreferences>().setString("darkTheme", dark ? "Y" : "");
+    Get.changeTheme(dark ? MyTheme.darkTheme : MyTheme.lightTheme);
+    Get.forceAppUpdate();
+  }
+
+  static bool _themeInitialed = false;
+
+  static ThemeData initialTheme({bool mainPage = false}) {
+    bool dark;
+    // Brightnesss is always light on windows, Flutter 3.0.5
+    if (_themeInitialed || !mainPage || Platform.isWindows) {
+      dark = isDarkTheme();
+    } else {
+      dark = WidgetsBinding.instance.platformDispatcher.platformBrightness ==
+          Brightness.dark;
+      Get.find<SharedPreferences>().setString("darkTheme", dark ? "Y" : "");
+    }
+    _themeInitialed = true;
+    return dark ? MyTheme.darkTheme : MyTheme.lightTheme;
+  }
+
   static ColorThemeExtension color(BuildContext context) {
     return Theme.of(context).extension<ColorThemeExtension>()!;
   }
@@ -201,6 +223,14 @@ class MyTheme {
   }
 }
 
+class ThemeModeNotifier {
+  final ValueNotifier<Brightness> brightness;
+  ThemeModeNotifier(this.brightness);
+  changeThemeBrightness({required Brightness brightness}) {
+    this.brightness.value = brightness;
+  }
+}
+
 bool isDarkTheme() {
   final isDark = "Y" == Get.find<SharedPreferences>().getString("darkTheme");
   return isDark;
diff --git a/flutter/lib/desktop/pages/desktop_setting_page.dart b/flutter/lib/desktop/pages/desktop_setting_page.dart
index 48fc0a5e7..a6ae89d71 100644
--- a/flutter/lib/desktop/pages/desktop_setting_page.dart
+++ b/flutter/lib/desktop/pages/desktop_setting_page.dart
@@ -224,21 +224,18 @@ class _UserInterfaceState extends State<_UserInterface>
   }
 
   Widget theme() {
-    var change = () {
-      bool dark = !isDarkTheme();
-      Get.changeTheme(dark ? MyTheme.darkTheme : MyTheme.lightTheme);
-      Get.find<SharedPreferences>().setString("darkTheme", dark ? "Y" : "");
-      Get.forceAppUpdate();
-    };
+    change() {
+      MyTheme.changeTo(!isDarkTheme());
+    }
 
     return GestureDetector(
+      onTap: change,
       child: Row(
         children: [
           Checkbox(value: isDarkTheme(), onChanged: (_) => change()),
           Expanded(child: Text(translate('Dark Theme'))),
         ],
       ).marginOnly(left: _kCheckBoxLeftMargin),
-      onTap: change,
     );
   }
 }
diff --git a/flutter/lib/desktop/pages/desktop_tab_page.dart b/flutter/lib/desktop/pages/desktop_tab_page.dart
index 87082284b..fde543a89 100644
--- a/flutter/lib/desktop/pages/desktop_tab_page.dart
+++ b/flutter/lib/desktop/pages/desktop_tab_page.dart
@@ -33,7 +33,6 @@ class _DesktopTabPageState extends State<DesktopTabPage> {
 
   @override
   Widget build(BuildContext context) {
-    final dark = isDarkTheme();
     RxBool fullscreen = false.obs;
     Get.put(fullscreen, tag: 'fullscreen');
     return Obx(() => DragToResizeArea(
diff --git a/flutter/lib/main.dart b/flutter/lib/main.dart
index 5ec2da9f8..a25ed7027 100644
--- a/flutter/lib/main.dart
+++ b/flutter/lib/main.dart
@@ -71,10 +71,6 @@ Future<Null> main(List<String> args) async {
   }
 }
 
-ThemeData getCurrentTheme() {
-  return isDarkTheme() ? MyTheme.darkTheme : MyTheme.lightTheme;
-}
-
 Future<void> initEnv(String appType) async {
   await platformFFI.init(appType);
   // global FFI, use this **ONLY** for global configuration
@@ -117,7 +113,7 @@ void runRemoteScreen(Map<String, dynamic> argument) async {
     navigatorKey: globalKey,
     debugShowCheckedModeBanner: false,
     title: 'RustDesk - Remote Desktop',
-    theme: getCurrentTheme(),
+    theme: MyTheme.initialTheme(),
     home: DesktopRemoteScreen(
       params: argument,
     ),
@@ -135,7 +131,7 @@ void runFileTransferScreen(Map<String, dynamic> argument) async {
       navigatorKey: globalKey,
       debugShowCheckedModeBanner: false,
       title: 'RustDesk - File Transfer',
-      theme: getCurrentTheme(),
+      theme: MyTheme.initialTheme(),
       home: DesktopFileTransferScreen(params: argument),
       navigatorObservers: [
         // FirebaseAnalyticsObserver(analytics: analytics),
@@ -152,7 +148,7 @@ void runPortForwardScreen(Map<String, dynamic> argument) async {
       navigatorKey: globalKey,
       debugShowCheckedModeBanner: false,
       title: 'RustDesk - Port Forward',
-      theme: getCurrentTheme(),
+      theme: MyTheme.initialTheme(),
       home: DesktopPortForwardScreen(params: argument),
       navigatorObservers: [
         // FirebaseAnalyticsObserver(analytics: analytics),
@@ -176,7 +172,7 @@ void runConnectionManagerScreen() async {
   ]);
   runApp(GetMaterialApp(
       debugShowCheckedModeBanner: false,
-      theme: getCurrentTheme(),
+      theme: MyTheme.initialTheme(),
       home: DesktopServerPage(),
       builder: _keepScaleBuilder()));
 }
@@ -191,7 +187,26 @@ WindowOptions getHiddenTitleBarWindowOptions(Size size) {
   );
 }
 
-class App extends StatelessWidget {
+class App extends StatefulWidget {
+  @override
+  State<App> createState() => _AppState();
+}
+
+class _AppState extends State<App> {
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.window.onPlatformBrightnessChanged = () {
+      WidgetsBinding.instance.handlePlatformBrightnessChanged();
+      var system =
+          WidgetsBinding.instance.platformDispatcher.platformBrightness;
+      var current = isDarkTheme() ? Brightness.dark : Brightness.light;
+      if (current != system) {
+        MyTheme.changeTo(system == Brightness.dark);
+      }
+    };
+  }
+
   @override
   Widget build(BuildContext context) {
     // final analytics = FirebaseAnalytics.instance;
@@ -210,7 +225,7 @@ class App extends StatelessWidget {
         navigatorKey: globalKey,
         debugShowCheckedModeBanner: false,
         title: 'RustDesk',
-        theme: getCurrentTheme(),
+        theme: MyTheme.initialTheme(mainPage: true),
         home: isDesktop
             ? const DesktopTabPage()
             : !isAndroid