function ScrollDataGrid() 
        { 
            var tb = document.getElementById("tbHeader"); 
            var dg = document.getElementById("dgSearchResult"); 
             
            if(dg!= null) 
            {     
                var dv = document.getElementById("dvBody"); 
                var th = dg.rows[0]; 
                for(var i = 0 ; i < th.cells.length;i++) 
                    th.cells[i].width = th.cells[i].clientWidth; 
                var tr = th.cloneNode(true); 
                 
                //tr.applyElement(tb); 
                tb.createTHead(); 
                var tbh = tb.tHead; 
                tbh.appendChild(tr); 
                tr = tbh.rows[0]; 
                var td = tr.insertCell(); 
                td.style.width = 19; 
                td.width = 19; 
                td.innerHTML = tr.cells[0].innerHTML; 
                th.style.display = 'none'; 
                if(dg.scrollHeight < 300 ) 
                    dv.style.height = dg.scrollHeight * 1 + 2; 
                 
                 
            } 

<table width="100%" border="0" id="tbHeader" cellpadding="4" cellspacing="0"> 
                                        </table> 
                                        <div style="OVERFLOW-Y: scroll; HEIGHT: 300px" id="dvBody"> 
                                            <asp:datagrid id="dgSearchResult" style="BORDER-COLLAPSE: collapse" runat="server" Width="100%" CellPadding="4" DataKeyField="编号" BorderWidth="1px" BorderStyle="Solid" BorderColor="RoyalBlue" GridLines="None"> 
                                                <SelectedItemStyle ForeColor="SlateGray"></SelectedItemStyle> 
                                                <ItemStyle VerticalAlign="Middle"></ItemStyle> 
                                                <HeaderStyle HorizontalAlign="Center"></HeaderStyle> 
                                                <Columns> 
                                                    <asp:ButtonColumn Text="选择" HeaderText="&lt;font face=webdings&gt;6&lt;/font&gt;" CommandName="Delete"> 
                                                        <HeaderStyle Wrap="False" Width="40px"></HeaderStyle> 
                                                        <ItemStyle Wrap="False" HorizontalAlign="Center"></ItemStyle> 
                                                        <FooterStyle Wrap="False"></FooterStyle> 
                                                    </asp:ButtonColumn> 
                                                </Columns> 
                                            </asp:datagrid></div>