方法一：
 
///
         /// 浏览器屏幕信息类
         ///
         public class Browser
        {
                 ///         
                 /// During static instantiation, only the Netscape flag is checked        
                 ///         
                 static Browser()
                {
                        _isNavigator = HtmlPage.BrowserInformation.Name.Contains( "Netscape");
                }
                 ///         
                 /// Flag indicating Navigator/Firefox/Safari or Internet Explorer        
                 ///         
                 private static bool _isNavigator;
                 ///         
                 /// Provides quick access to the window.screen ScriptObject        
                 ///         
                 private static ScriptObject Screen
                {
                        get
                        {
                                ScriptObject screen = (ScriptObject)HtmlPage.Window.GetProperty( "screen");
                                 if (screen == null)
                                {
                                         throw new InvalidOperationException();
                                }
                                 return screen;
                        }
                }
                 ///         
                 /// Gets the window object's client width        
                 ///         
                 public static double ClientWidth
                {
                        get
                        {
                                 return _isNavigator ? ( double)HtmlPage.Window.GetProperty( "innerWidth")
                                        : ( double)HtmlPage.Document.Body.GetProperty( "clientWidth");
                        }
                }
                 ///         
                 /// Gets the window object's client height        
                 ///         
                 public static double ClientHeight
                {
                        get
                        {
                                 return _isNavigator ? ( double)HtmlPage.Window.GetProperty( "innerHeight")
                                        : ( double)HtmlPage.Document.Body.GetProperty( "clientHeight");
                        }
                }
                 ///         
                 /// Gets the current horizontal scrolling offset        
                 ///         
                 public static double ScrollLeft
                {
                        get
                        {
                                 return _isNavigator ? ( double)HtmlPage.Window.GetProperty( "pageXOffset")
                                        : ( double)HtmlPage.Document.Body.GetProperty( "scrollLeft");
                        }
                }
                 ///         
                 /// Gets the current vertical scrolling offset        
                 ///         
                 public static double ScrollTop
                {
                        get
                        {
                                 return _isNavigator ? ( double)HtmlPage.Window.GetProperty( "pageYOffset")
                                        : ( double)HtmlPage.Document.Body.GetProperty( "scrollHeight");
                        }
                }
                 ///         
                 /// Gets the width of the entire display        
                 ///         
                 public static double ScreenWidth
                {
                        get
                        {
                                 return ( double)Screen.GetProperty( "width");
                        }
                }
                 ///         
                 /// Gets the height of the entire display        
                 ///         
                 public static double ScreenHeight
                {
                        get
                        {
                                 return ( double)Screen.GetProperty( "height");
                        }
                }
                 ///         
                 /// Gets the width of the available screen real estate, excluding the dock        
                 /// or task bar        
                 ///         
                 public static double AvailableScreenWidth
                {
                        get
                        {
                                 return ( double)Screen.GetProperty( "availWidth");
                        }
                }
                 ///         
                 /// Gets the height of the available screen real estate, excluding the dock /// or task bar        
                 ///         
                 public static double AvailableScreenHeight
                {
                        get
                        {
                                 return ( double)Screen.GetProperty( "availHeight");
                        }
                }
                 ///         
                 /// Gets the absolute left pixel position of the window in display coordinates        
                 ///         
                 public static double ScreenPositionLeft
                {
                        get
                        {
                                 return _isNavigator ? ( double)HtmlPage.Window.GetProperty( "screenX")
                                        : ( double)HtmlPage.Window.GetProperty( "screenLeft");
                        }
                }
                 ///         
                 /// Gets the absolute top pixel position of the window in display coordinates        
                 ///         
                 public static double ScreenPositionTop
                {
                        get
                        {
                                 return _isNavigator ? ( double)HtmlPage.Window.GetProperty( "screenY")
                                        : ( double)HtmlPage.Window.GetProperty( "screenTop");
                        }
                }
        }

方法二：
                  
 double    screenWidth = ( double)HtmlPage.Window.Eval( "screen.Width");    
  double screenHeight = ( double)HtmlPage.Window.Eval( "screen.Height");