protected void  CheckBox1_CheckedChanged(object sender, EventArgs e)
        {
            if (CheckBox1.Checked == true)
            {
                CheckBox1.Text = "选中";
            }
            else
            {
                CheckBox1.Text = "没选";
            }
        }

------解决方案--------------------
CheckBoxList的话这样
前台
C# code

 <asp:CheckBoxList ID="CheckBoxList1" runat="server" AutoPostBack="True" 
        onselectedindexchanged="CheckBoxList1_SelectedIndexChanged">
        <asp:ListItem Value="1">没选</asp:ListItem>
        <asp:ListItem Value="2">没选</asp:ListItem>
        <asp:ListItem Value="3">没选</asp:ListItem>
        <asp:ListItem Value="4">没选</asp:ListItem>
    </asp:CheckBoxList>