1.页面设置gridview ShowHeaderWhenEmpty="True"

2.参考原文：https://blog.csdn.net/xfblue/article/details/3861242

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.UI.WebControls;

/// <summary>
/// GridviewControl 的摘要说明
/// </summary>
public class GridviewControl
{
//当Gridview数据为空时显示的信息
private static string EmptyText = "没有记录";

public GridviewControl()
{

}

///<summary>
///防止PostBack后Gridview不能显示
///</summary>
///<param name="gridview"></param>
public static void ResetGridView(GridView gridview)
{
//如果数据为空则重新构造Gridview
if (gridview.Rows.Count == 1 && gridview.Rows[0].Cells[0].Text == EmptyText)
{
int columnCount = gridview.Columns.Count;
gridview.Rows[0].Cells.Clear();
gridview.Rows[0].Cells.Add(new TableCell());
gridview.Rows[0].Cells[0].ColumnSpan = columnCount;
gridview.Rows[0].Cells[0].Text = EmptyText;
gridview.Rows[0].Cells[0].Style.Add("text-align", "center");
}
}

///<summary>
///绑定数据到GridView，当表格数据为空时显示表头
///</summary>
///<param name="gridview"></param>
///<param name="table"></param>
public static void GridViewDataBind(GridView gridview, DataTable table)
{
//记录为空重新构造Gridview
if (table.Rows.Count == 0)
{
table = table.Clone();
table.Rows.Add(table.NewRow());
gridview.DataSource = table;
gridview.DataBind();
int columnCount = table.Columns.Count;
gridview.Rows[0].Cells.Clear();
gridview.Rows[0].Cells.Add(new TableCell());
gridview.Rows[0].Cells[0].ColumnSpan = columnCount;
gridview.Rows[0].Cells[0].Text = "没有记录";
gridview.Rows[0].Cells[0].Style.Add("text-align", "center");
}
else
{
//数据不为空直接绑定
//gridview.DataSource = table;
//gridview.DataBind();
}

//重新绑定取消选择
gridview.SelectedIndex = -1;
}
}