点一下添加label，点一下添加label...............

<asp:Button ID="Button4" runat="server" OnClick="Button4_Click" Text="后台调用" />
 <asp:Panel ID="Panel1" runat="server"></asp:Panel>

 protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                ViewState["max"] = 1;
            }
        }

    protected void Button4_Click(object sender, EventArgs e)
        {
            int max = Convert.ToInt32(ViewState["max"]);
            for (int i = 0; i < max; i++)
            {
                Label l = new Label();
                l.ID = "lbl" + i;
                l.Text = "label";
                Panel1.Controls.Add(l);
            }
            ViewState["max"] = max + 1;
        }