protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
  {
      if (e.Row.RowType == DataControlRowType.DataRow)
      {
          e.Row.Cells[0].Text = "******"; //假如Cells[0]是密码列
      }
  }

------解决方案--------------------

当然哪列标题还是密码单不绑定密码字段，直接绑定“***”
C# code

//添加一个TemplateField列
        <asp:GridView ID="GridView1" runat="server" ondatabound="GridView1_DataBound"            
            AutoGenerateColumns="False">
            <Columns>
                <asp:TemplateField HeaderText="密码">
                    <ItemTemplate>
                        ***
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>