方法如下:
在窗体的Load事件注册滚动事件,并增加对应的方法 
        /// <summary>
        /// 滚动方法
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void FormSample_MouseWheel(object sender, MouseEventArgs e)
        {
            //获取光标位置
            Point mousePoint = new Point(e.X,e.Y);
            //换算成相对本窗体的位置
            mousePoint.Offset(this.Location.X, this.Location.Y);       
            //判断是否在panel内
            if (pnlDownload.RectangleToScreen(
              pnlDownload.DisplayRectangle).Contains(mousePoint))
            {
                //滚动
                pnlDownload.AutoScrollPosition = new Point(
, pnlDownload.VerticalScroll.Value - e.Delta);
            }
        }
</div>

