diff --git a/src/PlayerViewModel.cpp b/src/PlayerViewModel.cpp
index 339e37d..541ca83 100644
--- a/src/PlayerViewModel.cpp
+++ b/src/PlayerViewModel.cpp
@@ -8,6 +8,8 @@ namespace winrt::Player::implementation
 {
     PlayerViewModel::PlayerViewModel() {
         volume_ = SettingsHelper::GetVolume();
+        position_ = 0.;
+        duration_ = 0.;
     }
     double PlayerViewModel::Volume()
     {
@@ -16,6 +18,24 @@ namespace winrt::Player::implementation
     uint32_t PlayerViewModel::Index() {
         return index_;
     }
+    double PlayerViewModel::Position() {
+        return position_;
+    }
+    void PlayerViewModel::Position(double value) {
+        if (value != position_) {
+            position_ = value;
+            propertyChanged_(*this, winrt::Microsoft::UI::Xaml::Data::PropertyChangedEventArgs{ L"Position" });
+        }
+    }
+    double PlayerViewModel::Duration() {
+        return duration_;
+    }
+    void PlayerViewModel::Duration(double value) {
+        if (value != duration_) {
+            duration_ = value;
+            propertyChanged_(*this, winrt::Microsoft::UI::Xaml::Data::PropertyChangedEventArgs{ L"Duration" });
+        }
+    }
     void PlayerViewModel::Index(uint32_t value) {
         if (value != index_) {
             index_ = value;
@@ -32,6 +52,14 @@ namespace winrt::Player::implementation
     winrt::hstring PlayerViewModel::DoubleToString(double value) {
         return fast_io::wconcat_winrt_hstring(value);
     }
+    winrt::hstring PlayerViewModel::DurationToString(double value) {
+         auto const hms{ std::chrono::hh_mm_ss{std::chrono::nanoseconds{static_cast<int64_t>(value) * 100}} };
+         auto hours{ hms.hours().count() };
+         if (hours)
+             return fast_io::wconcat_winrt_hstring(fast_io::mnp::right(hours, 2, L'0'), fast_io::mnp::chvw(L':'), fast_io::mnp::right(hms.minutes().count(), 2, L'0'), fast_io::mnp::chvw(L':'), fast_io::mnp::right(hms.seconds().count(), 2, L'0'));
+         else
+             return fast_io::wconcat_winrt_hstring(fast_io::mnp::right(hms.minutes().count(), 2, L'0'), fast_io::mnp::chvw(L':'), fast_io::mnp::right(hms.seconds().count(), 2, L'0'));
+    }
     winrt::event_token PlayerViewModel::PropertyChanged(winrt::Microsoft::UI::Xaml::Data::PropertyChangedEventHandler const& handler)
     {
         return propertyChanged_.add(handler);
diff --git a/src/PlayerViewModel.h b/src/PlayerViewModel.h
index b31de46..be55377 100644
--- a/src/PlayerViewModel.h
+++ b/src/PlayerViewModel.h
@@ -10,12 +10,19 @@ namespace winrt::Player::implementation
         void Volume(double value);
         uint32_t Index();
         void Index(uint32_t value);
+        double Position();
+        void Position(double value);
+        double Duration();
+        void Duration(double value);
         winrt::event_token PropertyChanged(winrt::Microsoft::UI::Xaml::Data::PropertyChangedEventHandler const& handler);
         void PropertyChanged(winrt::event_token const& token) noexcept;
         static winrt::hstring DoubleToString(double);
+        static winrt::hstring DurationToString(double);
     private:
         double volume_;
         uint32_t index_;
+        double position_;
+        double duration_;
         winrt::event<winrt::Microsoft::UI::Xaml::Data::PropertyChangedEventHandler> propertyChanged_;
     };
 }
diff --git a/src/PlayerViewModel.idl b/src/PlayerViewModel.idl
index ab7385d..a7f1139 100644
--- a/src/PlayerViewModel.idl
+++ b/src/PlayerViewModel.idl
@@ -7,6 +7,9 @@ namespace Player
         PlayerViewModel();
         Double Volume;
         UInt32 Index;
+        Double Position;
+        Double Duration;
         static String DoubleToString(Double volume);
+        static String DurationToString(Double duration);
     }
 }
diff --git a/src/RootPage.xaml b/src/RootPage.xaml
index 7239f03..19dffcf 100644
--- a/src/RootPage.xaml
+++ b/src/RootPage.xaml
@@ -188,18 +188,23 @@
                     HorizontalAlignment="Center"
                     VerticalAlignment="Center"
                     FontSize="11"
-                    Text="0:00:00" />
+                    Text="{x:Bind local:PlayerViewModel.DurationToString(local:RootPage.PlayerViewModel.Position), Mode=OneWay}" />
                 <Slider
+                    Name="PlayerSlider"
                     Grid.Column="1"
                     Margin="0"
-                    HorizontalAlignment="Stretch" />
+                    HorizontalAlignment="Stretch"
+                    IsThumbToolTipEnabled="False"
+                    Maximum="{x:Bind local:RootPage.PlayerViewModel.Duration, Mode=OneWay}"
+                    StepFrequency="1000"
+                    Value="{x:Bind local:RootPage.PlayerViewModel.Position, Mode=TwoWay}" />
                 <TextBlock
                     x:Uid="RemainingTime"
                     Grid.Column="2"
                     HorizontalAlignment="Center"
                     VerticalAlignment="Center"
                     FontSize="11"
-                    Text="0:00:00" />
+                    Text="{x:Bind local:PlayerViewModel.DurationToString(local:RootPage.PlayerViewModel.Duration), Mode=OneWay}" />
             </Grid>
             <Button
                 x:Uid="Playing"
diff --git a/src/RootPage.xaml.cpp b/src/RootPage.xaml.cpp
index 89991d0..7d72dd9 100644
--- a/src/RootPage.xaml.cpp
+++ b/src/RootPage.xaml.cpp
@@ -19,16 +19,20 @@ namespace winrt::Player::implementation
     RootPage::RootPage()
     {
         InitializeComponent();
-
+        playerViewModel_ = winrt::Player::PlayerViewModel{};
+        player_ = winrt::Windows::Media::Playback::MediaPlayer{};
+        player_.AudioCategory(Windows::Media::Playback::MediaPlayerAudioCategory::Media);
+        session_ = player_.PlaybackSession();
+        commander_ = player_.CommandManager();
+        list_ = winrt::Windows::Media::Playback::MediaPlaybackList{};
+        list_.MaxPlayedItemsToKeepOpen(3);
+        player_.Source(list_);
+        music_ = list_.Items();
         // init state
         if (SettingsHelper::CheckFirstUse()) [[unlikely]] {
             RootFrame().Navigate(winrt::xaml_typename<Player::Welcome>());
             MainNavigation().IsPaneOpen(false);
             }
-            // set player
-        list_.MaxPlayedItemsToKeepOpen(3);
-        player_.Source(list_);
-        player_.AudioCategory(Windows::Media::Playback::MediaPlayerAudioCategory::Media);
 
         InitializeLibraries();
         InitializeRegistEvent();
@@ -88,6 +92,30 @@ namespace winrt::Player::implementation
         playerViewModel_.PropertyChanged([&self = *this](IInspectable const&, PropertyChangedEventArgs const&) {
             self.player_.Volume(self.playerViewModel_.Volume() / 100.);
             });
+        // slider
+        session_.PlaybackStateChanged([&self = *this, ui_thread = winrt::apartment_context{}](decltype(session_) const& sender, IInspectable const&) -> IAsyncAction {
+            auto state{ self.session_.PlaybackState() };
+            using namespace std::chrono_literals;
+            if (state == decltype(state)::Playing) [[likely]] {
+                auto index{ list_.CurrentItemIndex() };
+                auto info{ self.info_list_.GetAt(index) };
+                co_await ui_thread;
+                self.playerViewModel_.Duration(static_cast<double>(info.Duration));
+            }
+            while (self.session_.PlaybackState() == decltype(self.session_.PlaybackState())::Playing) [[likely]] {
+                using namespace std::chrono_literals;
+                co_await 1s;
+                co_await ui_thread;
+                auto position{ self.session_.Position().count() };
+                if (position > 0) [[likely]] {
+                    self.playerViewModel_.Position(static_cast<double>(position));
+                    }
+                }
+            });
+        playerViewModel_.PropertyChanged([&self = *this, ui_thread = winrt::apartment_context{}](IInspectable const&, PropertyChangedEventArgs const& args) {
+            if (args.PropertyName() != L"Position") return;
+            self.session_.Position(std::chrono::duration_cast<decltype(self.session_.Position())>(std::chrono::nanoseconds{ static_cast<int64_t>(self.playerViewModel_.Position()) * 100 }));
+            });
         // when switch to new music, make button ui on
         list_.CurrentItemChanged([&self = *this, ui_thread = winrt::apartment_context{}](decltype(list_) const&, Windows::Media::Playback::CurrentMediaPlaybackItemChangedEventArgs const& args) -> IAsyncAction {
             auto reason{ args.Reason() };
diff --git a/src/RootPage.xaml.h b/src/RootPage.xaml.h
index 988a311..01d5ee9 100644
--- a/src/RootPage.xaml.h
+++ b/src/RootPage.xaml.h
@@ -17,6 +17,7 @@ namespace winrt::Player::implementation
         static winrt::Windows::Foundation::Collections::IVector<winrt::Data::MusicInfo> InfoList();
         static winrt::Windows::Foundation::Collections::IObservableVector<winrt::Data::Library> Libraries();
         static winrt::Windows::Foundation::Collections::IObservableVector<Windows::Media::Playback::MediaPlaybackItem> Music();
+
         // events
         void Page_Loaded(winrt::Windows::Foundation::IInspectable const&, winrt::Microsoft::UI::Xaml::RoutedEventArgs const&);
         void Volume_LostFocus(winrt::Windows::Foundation::IInspectable const&, winrt::Microsoft::UI::Xaml::RoutedEventArgs const&);
@@ -48,14 +49,14 @@ namespace winrt::Player::implementation
         void InitializeLibraries();
         // rumtime properties implement
         winrt::hstring title_{L"PlayerWinRT"};
-        Windows::Media::Playback::MediaPlayer player_{};
-        winrt::Windows::Media::Playback::MediaPlaybackSession session_{ player_.PlaybackSession() };
-        winrt::Windows::Media::Playback::MediaPlaybackCommandManager commander_{ player_.CommandManager() };
+        Windows::Media::Playback::MediaPlayer player_{ nullptr };
+        winrt::Windows::Media::Playback::MediaPlaybackSession session_{ nullptr };
+        winrt::Windows::Media::Playback::MediaPlaybackCommandManager commander_{ nullptr };
         inline static winrt::Data::Library library_;
-        inline static winrt::Player::PlayerViewModel playerViewModel_;
-        inline static Windows::Media::Playback::MediaPlaybackList list_{};
+        inline static winrt::Player::PlayerViewModel playerViewModel_{ nullptr };
+        inline static Windows::Media::Playback::MediaPlaybackList list_{ nullptr };
         inline static winrt::Windows::Foundation::Collections::IObservableVector<winrt::Data::Library> libraries_{ nullptr };
-        inline static winrt::Windows::Foundation::Collections::IObservableVector<Windows::Media::Playback::MediaPlaybackItem> music_{list_.Items()};
+        inline static winrt::Windows::Foundation::Collections::IObservableVector<Windows::Media::Playback::MediaPlaybackItem> music_{ nullptr };
         inline static winrt::Windows::Foundation::Collections::IVector<winrt::Data::MusicInfo> info_list_{ winrt::single_threaded_vector<winrt::Data::MusicInfo>() };
     };
 }