public void DataTable2Excel(DataTable dtData)

        {

            if (dtData != null)

            {

                Response.Clear();

                Response.Charset = "utf-8";

                Response.AppendHeader("Content-Disposition", "attachment;filename= " + Server.UrlEncode("导出.xls"));

                Response.ContentEncoding = System.Text.Encoding.GetEncoding("utf-8");

                Response.ContentType = "application/ms-excel";//设置输出文件类型为excel文件.

                this.EnableViewState = false;

                System.Globalization.CultureInfo myCItrad = new System.Globalization.CultureInfo("ZH-CN", true);

                System.IO.StringWriter stringWrite = new System.IO.StringWriter(myCItrad);

                System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);

                //// 为了解决dgData中可能进行了分页的情况，需要重新定义一个无分页的DataGrid

                //System.Web.UI.WebControls.GridView dgExport = null;

                //dgExport = new System.Web.UI.WebControls.GridView();

                GridView dgExport = new GridView();

                dgExport.AllowPaging = false;

                dgExport.DataSource = dtData;

                dgExport.DataBind();

                for (int i = 1; i < dgExport.Rows.Count; i++)

                {

                    dgExport.Rows[i].Cells[0].Attributes.Add("style", "mso-number-format:'0'");

                    dgExport.Rows[i].Cells[2].Attributes.Add("style", "mso-number-format:'\\@'");

                }

                dgExport.RenderControl(htmlWrite);

                Response.Write(stringWrite.ToString());

               Response.Write(@"<style> .text { mso-number-format:'\\@';} </script> ");

                Response.End();   

            }

        }

GridView export to excel 格式参考

mso-number-format:"0" NO Decimals

mso-number-format:"0\.000" 3 Decimals

mso-number-format:"\#\,\#\#0\.000" Comma with 3 dec

mso-number-format:"mm\/dd\/yy" Date7

mso-number-format:"mmmm\ d\,\ yyyy" Date9

mso-number-format:"m\/d\/yy\ h\:mm\ AM\/PM" D -T AMPM

mso-number-format:"Short Date" 01/03/1998

mso-number-format:"Medium Date" 01-mar-98

mso-number-format:"d\-mmm\-yyyy" 01-mar-1998

mso-number-format:"Short Time" 5:16

mso-number-format:"Medium Time" 5:16 am

mso-number-format:"Long Time" 5:16:21:00

mso-number-format:"Percent" Percent - two decimals

mso-number-format:"0%" Percent - no decimals

mso-number-format:"0\.E+00" Scientific Notation

mso-number-format:"\@" Text

mso-number-format:"\#\ ???\/???" Fractions - up to 3 digits (312/943)

mso-number-format:"\0022?\0022\#\,\#\#0\.00" ?12.76

mso-number-format:"\#\,\#\#0\.00_ \;\[Red\]\-\#\,\#\#0\.00\ " 2 decimals, negative numbers in red and signed

(1.56   -1.56)