<form id="form1" runat="server">
  <asp:ScriptManager ID="ScriptManager1" runat="server">
  </asp:ScriptManager>
      <asp:UpdatePanel ID="UpdatePanel1" runat="server">
      <ContentTemplate>
        <asp:Timer ID="Timer1" runat="server" Interval="60000" ontick="Timer1_Tick">
        </asp:Timer>
      </ContentTemplate>
      </asp:UpdatePanel>
</form>

protected void Page_Load(object sender, EventArgs e)
{}
protected void Timer1_Tick(object sender, EventArgs e)
{
//这里可以操作你想做的事情，比如定时查询数据库
ScriptManager.RegisterStartupScript(this, this.GetType(), "", "alert('Hello‘);", true);
}