<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
        <Columns>
            <asp:BoundField DataField="ss"  />
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:DropDownList ID="DropDownList2" runat="server"  AutoPostBack="true"
                        onselectedindexchanged="DropDownList2_SelectedIndexChanged">
                        <asp:ListItem>sss</asp:ListItem>
                        <asp:ListItem>eee</asp:ListItem>
                    </asp:DropDownList>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>