private const string strConn = "自己写连接字符串";
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            BindDataToGridView();
        }
    }

    /// <summary>
    /// 绑定
    /// </summary>
    private void BindDataToGridView()
    {
        SqlConnection conn = new SqlConnection(strConn);
        string strSQL = "select * from [User]";
        SqlDataAdapter da = new SqlDataAdapter(strSQL, conn);
        DataSet ds = new DataSet();
        da.Fill(ds, "[User]");
        this.GridView1.DataSource = ds;
        this.GridView1.DataKeyNames = new string[] { "UserId" };
        this.GridView1.DataBind();
    }

    /// <summary>
    /// 导出DataSet到Execl
    /// </summary>
    private void OutExecl()
    {
        Excel.Application myExcel = new Excel.Application();
        myExcel.Visible = true;

        if (myExcel == null)
        {
            Page.RegisterStartupScript("", "<script>alert('EXCEL无法启动');</script>");
        }

        Workbook work = myExcel.Application.Workbooks.Add(Type.Missing);
        Worksheet sheet = (Worksheet)work.Worksheets[1];

        int rowCount = 0; 
        int columnCount = 0; 

        columnCount = this.GridView1.Columns.Count; 
        rowCount = this.GridView1.Rows.Count;  

        rowCount--;

        for (int m = 1; m < columnCount; m++)   
        {
            sheet.Cells[1, m] = this.GridView1.Columns[m].HeaderText;//得到列标题文本
        }

        for (int i = 0; i <= rowCount; i++)  //二维表填充从每一行开始
        {
            for (int j = 1; j < columnCount; j++)      //填充每一行第j列单元格，循环添加行列数据
            {
                sheet.Cells[i + 2, j] = this.GridView1.Rows[i].Cells[j].Text; 
            }
        }
        Page.RegisterStartupScript("", "<script>alert('成功导出！');</script>");
    }

    /// <summary>
    /// 导出
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void btnOut_Click(object sender, EventArgs e)
    {
        OutExecl();
    }

    /// <summary>
    /// 导入Excel到DataSet
    /// </summary>
    /// <param name="filePath"></param>
    /// <returns></returns>
    private DataSet InExecl(string filePath)
    {
        DataSet ds = new DataSet();
        string connStr = "Provider = Microsoft.Jet.OLEDB.4.0; Data Source = " + filePath + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=1\"";

        OleDbConnection myConn = new OleDbConnection(connStr);
        string strSQL = " SELECT * FROM [Sheet1$]";
        myConn.Open();
        OleDbDataAdapter myCommand = new OleDbDataAdapter(strSQL, myConn);
        DataSet myDataSet = new DataSet();
        myCommand.Fill(myDataSet, "[Sheet1$]");
        myConn.Close();

        return myDataSet;
    }
    
    /// <summary>
    /// 导入
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void btnIn_Click(object sender, EventArgs e)
    {
        DataSet ds = InExecl(this.File1.PostedFile.FileName);
        this.GridView2.DataSource = ds;
        this.GridView2.DataBind();
    }
}

------解决方案--------------------

 private static DataSet NewMethod(string ExcelName, string Sheet)  
       {  
           DataSet dsE = new DataSet();  
           string MyConnectionstring = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + @System.Web.HttpContext.Current.Server.MapPath("ExcelTemp") + @"\" + ExcelName+ "