在构造函数中添加事件:
webBrowser.DocumentCompleted+=new WebBrowserDocumentCompletedEventHandler(webBrowser_DocumentCompleted);
void webBrowser_DocumentCompleted(object sender, System.Windows.Forms.WebBrowserDocumentCompletedEventArgs e)
{
//滚动到制定位置
webBrowser.Document.Window.ScrollTo(0, 1000);
}