方法一

aspx

GridView 添加 

OnDataBound="GridView1_DataBound"

和

<asp:TemplateField ItemStyle-Width="50px" ItemStyle-HorizontalAlign="Center">

                    <HeaderTemplate>

                        序号</HeaderTemplate>

                    <ItemTemplate>

                        <asp:Label ID="Label1" runat="server" Text=""></asp:Label>

                    </ItemTemplate>

                </asp:TemplateField>

 aspx.cs

加入

protected void GridView1_DataBound(object sender, EventArgs e)

        {

            int num = GridView1.Rows.Count;

            for (int i = 0; i < num; i++)

            {

                Label lbl = (Label)GridView1.Rows[i].FindControl("Label1");

                lbl.Text = (i+1).ToString();

            }

        }

方法二（简单）：

<asp:TemplateField ItemStyle-Width="50px" ItemStyle-HorizontalAlign="Center">

                    <HeaderTemplate>

                        序号</HeaderTemplate>

                    <ItemTemplate>

                        <%#Container.DataItemIndex+1 %></ItemTemplate>

 </asp:TemplateField>

 OK