用楼主所说做了简单的时钟效果,并没有出现页面闪烁的问题啊,这是页面生成代码:        
<asp:ScriptManager ID="ScriptManager1" runat="server" />
        <asp:Timer ID="Timer1" runat="server" OnTick="Timer1_Tick" Interval="1000">
        </asp:Timer>
        <div>
            <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
                <ContentTemplate>
                    <asp:Label ID="Label1" runat="server"></asp:Label>
                </ContentTemplate>
                <Triggers>
                    <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />
                </Triggers>
            </asp:UpdatePanel>
        </div>