#region 合并单元格 合并某一行的所有列
    public static void GroupRow(GridView gridView)
    {
        for (int rowIndex = gridView.Rows.Count - 2; rowIndex >= 0; rowIndex--)
        {
            GridViewRow row = gridView.Rows[rowIndex];
            GridViewRow previousRow = gridView.Rows[rowIndex + 1];
            for (int i = 0; i < row.Cells.Count; i++)
            {
                if (row.Cells[i].Text == previousRow.Cells[i].Text)
                {
                    row.Cells[i].RowSpan = previousRow.Cells[i].RowSpan < 2 ? 2 :
                                           previousRow.Cells[i].RowSpan + 1;
                    previousRow.Cells[i].Visible = false;
                }
            }
        }
    }
    ///　 <summary>　
    ///　 合并GridView中某行相同信息的行（单元格）
    ///　 </summary>　
    ///　 <param　 name="GridView1">GridView对象</param>　
    ///　 <param　 name="cellNum">需要合并的行</param>
    public static void GroupRow(GridView gridView, int rows)
    {
        TableCell oldTc = gridView.Rows[rows].Cells[0];
        for (int i = 1; i < gridView.Rows[rows].Cells.Count; i++)
        {
            TableCell tc = gridView.Rows[rows].Cells[i];　 //Cells[0]就是你要合并的列
            if (oldTc.Text == tc.Text)
            {
                tc.Visible = false;
                if (oldTc.ColumnSpan == 0)
                {
                    oldTc.ColumnSpan = 1;
                }
                oldTc.ColumnSpan++;
                oldTc.VerticalAlign = VerticalAlign.Middle;
            }
            else
            {
                oldTc = tc;
            }
        }
    }
    #endregion
    #region 合并单元格 合并一行中的几列
    /// <summary>
    /// 合并单元格 合并一行中的几列
    /// </summary>
    /// <param name="GridView1">GridView ID</param>
    /// <param name="rows">行</param>
    /// <param name="sCol">开始列</param>
    /// <param name="eCol">结束列</param>
    public static void GroupRow(GridView gridView, int rows, int sCol, int eCol)
    {
        TableCell oldTc = gridView.Rows[rows].Cells[sCol];
        for (int i = 1; i < eCol - sCol; i++)
        {
            TableCell tc = gridView.Rows[rows].Cells[i + sCol];　 //Cells[0]就是你要合并的列
            tc.Visible = false;
            if (oldTc.ColumnSpan == 0)
            {
                oldTc.ColumnSpan = 1;
            }
            oldTc.ColumnSpan++;
            oldTc.VerticalAlign = VerticalAlign.Middle;
        }
    }
    #endregion
    #region 合并单元格 合并某一列所有行
    /// <summary>
    /// 合并GridView中某列相同信息的行（单元格）
    /// </summary>
    /// <param name="GridView1"></param>
    /// <param name="cellNum"></param>
    public static void GroupCol(GridView gridView, int cols)
    {
        if (gridView.Rows.Count < 1 || cols > gridView.Rows[0].Cells.Count - 1)
        {
            return;
        }
        TableCell oldTc = gridView.Rows[0].Cells[cols];
        for (int i = 1; i < gridView.Rows.Count; i++)
        {
            TableCell tc = gridView.Rows[i].Cells[cols];
            if (oldTc.Text == tc.Text)
            {
                tc.Visible = false;
                if (oldTc.RowSpan == 0)
                {
                    oldTc.RowSpan = 1;
                }
                oldTc.RowSpan++;
                oldTc.VerticalAlign = VerticalAlign.Middle;
            }
            else
            {
                oldTc = tc;
            }
        }
    }
    #endregion
    #region 合并单元格 合并某一列中的某些行
    /// <summary>
    /// 合并单元格 合并某一列中的某些行
    /// </summary>
    /// <param name="GridView1">GridView ID</param>
    /// <param name="cellNum">列</param>
    /// <param name="sRow">开始行</param>
    /// <param name="eRow">结束列</param>
    public static void GroupCol(GridView gridView, int cols, int sRow, int eRow)
    {
        if (gridView.Rows.Count < 1 || cols > gridView.Columns.Count - 1)
        {
            return;
        }
        TableCell oldTc = gridView.Rows[sRow].Cells[cols];
        for (int i = 1; i < eRow - sRow; i++)
        {
            TableCell tc = gridView.Rows[sRow + i].Cells[cols];
            tc.Visible = false;
            if (oldTc.RowSpan == 0)
            {
                oldTc.RowSpan = 1;
            }
            oldTc.RowSpan++;
            oldTc.VerticalAlign = VerticalAlign.Middle;
        }
    }
    #endregion
}


以上方法在给GridView赋值时调用如：

           private void BindPurchaseOrders()
          {
        #region
        DataTable  ABC= s1.select("select * from Table ");
        GridView.DataSource = ABC;
        GridView.DataBind();

        GroupCol(GridView, 0);        //调用上面的方法（此方法为合并第一列相同数据的单元格）

        #endregion

 

       //按条件合并单元格
        for (int i = 0; i < ABC.Rows.Count; i++)   //循环所有数据
        {
        if (ABC.Rows[i]["A"].ToString() == ABC.Rows[i]["B"].ToString())    //如果A字段等于B字段那么合并单元格
        {

//假设A在第一列B在第二列，则调用合并方法，合并第一列和第二列相同数据的行
        GroupRow(GV_LowValue, i, 0, 1);
        }

        }

        }