第一步先引用 scriptManager

<asp:UpdatePanel ID="UpdatePanelGuanZhu" runat="server">
<ContentTemplate>

<asp:Button ID="cmdGuangZhu" runat="server" CssClass="ButtonWeiXin" Text="提交" OnClick="cmdGuangZhu_Click" />

</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="cmdGuangZhu" />
</Triggers>
</asp:UpdatePanel>

进度

<asp:UpdateProgress ID="UpdateProgress1" runat="server" >
<ProgressTemplate >

<div id="iLoading" style="font-weight: bold; font-size: large; left: 20px; text-transform: capitalize; color: red; font-family: Monospace; position: absolute; top: 50px; background-color: #99ccff;">

Loading......

</div>

</ProgressTemplate>
</asp:UpdateProgress>

后台执行事件的按钮代码里要加入 System.Threading.Thread.Sleep(2000);

asp.net ajax 简单案例