第一種： 

出處：http://hi.baidu.com/flc_709/blog/item/20976454869fd957574e0020.html

/// <summary>

/// 合并GridView中某列相同信息的行（單元格）  

/// </summary>

/// <param name="GridView1">GridView</param>

/// <param name="cellNum">第幾列</param>

       public static void GroupRows(GridView GridView1, int cellNum)
       {

           int i = 0, rowSpanNum = 1;

while (i < GridView1.Rows.Count - 1)
           {
               GridViewRow gvr = GridView1.Rows[i];

               for (++i; i < GridView1.Rows.Count; i++)
               {
                   GridViewRow gvrNext = GridView1.Rows[i];

                   if (gvr.Cells[cellNum].Text == gvrNext.Cells[cellNum].Text)
                   {
                       gvrNext.Cells[cellNum].Visible = false;
                       rowSpanNum++;
                   }

                   else
                   {
                       gvr.Cells[cellNum].RowSpan = rowSpanNum;
                       rowSpanNum = 1;
                       break;
                   }

                   if (i == GridView1.Rows.Count - 1)
                   {
                       gvr.Cells[cellNum].RowSpan = rowSpanNum;
                   }
               }
           }
       }

//正常換行
           GVbkdj.Attributes.Add("style", "word-break:keep-all;word-wrap:normal");
          //下面這行是自動換行       
         //GVbkdj.Attributes.Add("style", "word-break:break-all;word-wrap:break-word");

第二種方式：遞歸方式做成一個控件

public class GroupedGridView : GridView
    {  
        public int GroupedDepth
        {
            get
            {
                object val = this.ViewState["GroupedDepth"];
                if (null == val)
                {
                    return 0;
                }

                return (int)val;
            }
            set
            {
                if (value < 0)
                    throw new ArgumentOutOfRangeException("value", "value must be greater than or equal to zero");

                this.ViewState["GroupedDepth"] = value;
            }
        }

        protected override void OnDataBound(EventArgs e)
        {
            base.OnDataBound(e);

            this.SpanCellsRecursive(0, 0, this.Rows.Count);
        }

        private void SpanCellsRecursive(int columnIndex, int startRowIndex, int endRowIndex)
        {
            if (columnIndex >= this.GroupedDepth || columnIndex >= this.Columns.Count)
                return;

            TableCell groupStartCell = null;
            int groupStartRowIndex = startRowIndex;

            for (int i = startRowIndex; i < endRowIndex; i++)
            {
                TableCell currentCell = this.Rows[i].Cells[columnIndex];

                bool isNewGroup = (null == groupStartCell) || (0 != String.CompareOrdinal(currentCell.Text, groupStartCell.Text));

                if (isNewGroup)
                {
                    if (null != groupStartCell)
                    {
                        SpanCellsRecursive(columnIndex + 1, groupStartRowIndex, i);
                    }

                    groupStartCell = currentCell;
                    groupStartCell.RowSpan = 1;
                    groupStartRowIndex = i;
                }
                else
                {
                    currentCell.Visible = false;
                    groupStartCell.RowSpan += 1;
                }
            }

            SpanCellsRecursive(columnIndex + 1, groupStartRowIndex, endRowIndex);
        }
    }