1.在panel屬性將AutoScroll屬性設定為True

2.新增ControlAdded事件和Scroll事件

3.     private void panel3_Scroll(object sender, ScrollEventArgs e)
        {
            this.panel3.VerticalScroll.Value = e.NewValue;
            panel3.Invalidate();//重新整理panel
        }

4. private void panel3_ControlAdded(object sender, ControlEventArgs e)
        {
            this.panel3.VerticalScroll.Enabled = true;
            this.panel3.VerticalScroll.Visible = true;
            this.panel3.Scroll += panel3_Scroll;
        }