<asp:RadioButton ID="rbNewUser" runat="server" GroupName="user" Text="新用户注册"  />

<asp:RadioButton ID="rbExistUser" runat="server" GroupName="user" Text="已有用户注册"/>

var registType = $j("input[type='radio']:checked").next().text();

 <asp:RadioButtonList ID="rb_IsPublicPlan" runat="server"

                            RepeatColumns="" RepeatDirection="Horizontal" RepeatLayout="Flow" CssClass="formradio">

                            <asp:ListItem Value="">不公示</asp:ListItem>

                            <asp:ListItem Value="">公示</asp:ListItem>

                        </asp:RadioButtonList>

$('#<%=rb_IsPublicPlan.ClientID%>').find('input:checked').val();