My code:

void Media_MarkerReached(object sender, TimelineMarkerRoutedEventArgs e)
        {
            double time = e.Marker.Time.TotalSeconds;
            double seconds = Media.NaturalDuration.TimeSpan.TotalSeconds;
            if (time <= 0)
            {
                return;
            }
            double maker = time * SliderPosition.Maximum / seconds;
            //TxtTime.Text = e.Marker.Time.Minutes + ":" + e.Marker.Time.Seconds;
            TxtTime.Text = string.Format("{0:00}:{1:00}",Media.Position.Minutes,Media.Position.Seconds);
            if (Flage)
            {
                SliderPosition.Value = maker;
            }
        }
        void SliderPosition_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
        {
           
            double seconds = Media.NaturalDuration.TimeSpan.TotalSeconds;
            double tvalue = seconds / SliderPosition.Maximum * this.SliderPosition.Value;
            if (e.NewValue != tvalue)
            {
                double time = SliderPosition.Value / SliderPosition.Maximum * seconds;
                Media.Position = new TimeSpan(0, 0, (int)time);
            }
        }

The problem :MediaElement.MarkerReaded can change SliderPosition.Value  but change SliderPosition.Value 

You can remove the Marker reached eventHandler in slider valuechanged event.

Thanks
Rajesh Shirpuram

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No,it is not my meaning,Iwant to change silder's value  At same time change media's position  and when media'position was changed  change silder's value  also

Can give an example？

I have to solve the problem 3Q