UpdatePanel

 <asp:UpdatePanel ID="UpdatePanel1"  UpdateMode="Conditional" runat="server">       
                 <Triggers>
                   <asp:AsyncPostBackTrigger ControlID="Button1" />
                 </Triggers>
                 <ContentTemplate>
                 <fieldset>
                 <legend>UpdatePanel content</legend>
                 <%=DateTime.Now.ToString() %>
                     <asp:GridView ID="GridView1" runat="server">
                     </asp:GridView>
                 </fieldset>
                 </ContentTemplate>
        </asp:UpdatePanel>

微软的例子 还是很经典的