1.先要引用dll檔案，可以直接使用vs自帶的包管理，如下圖：

輸入 EPPlus

 我這裡是安裝過了的所以這裡顯示的是解除安裝而不是安裝。

安裝成功了之後會看到這個dll檔案

程式碼如下：

//匯出Excel
        protected void BtnMemExcel_Click(object sender, EventArgs e)
        {
            Mem bllMember = new Mem();
            int Counts = NetPagerParameter.RecordCount;
            
 
string strSql = QueryCondition();
            strSql += "and Mem.MemShopID = SysShop.ShopID and Mem.MemLevelID = MemLevel.LevelID and Mem.MemUserID = SysUser.UserID";
            strSql += (" and Mem.MemShopID =SysShopMemLevel.ShopID and SysShopMemLevel.MemLevelID=MemLevel.LevelID ");
            DataTable db 
 
= bllMember.GetListSP(100000, 1, out Counts, PubFunction.GetShopAuthority(_UserShopID, "MemShopID", strSql)).Tables[0];//講資料填充到table中
            
            //核心程式碼
            using (ExcelPackage package = new ExcelPackage())
            {
                ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("
 
Sheet");

                worksheet.Cells[1, 1].Value = "會員卡號";
                worksheet.Cells[1, 2].Value = "會員姓名";
                worksheet.Cells[1, 3].Value = "會員餘額" + DateTime.Now.ToString("yyyy-MM-dd HH:mmssffff");
                for (int i = 2; i < db.Rows.Count + 2; i++)
                {
                    worksheet.Cells[i, 1].Value = db.Rows[i - 2]["MemCard"];
                    worksheet.Cells[i, 2].Value = db.Rows[i - 2]["MemName"];
                    worksheet.Cells[i, 3].Value = db.Rows[i - 2]["MemMobile"];
                    worksheet.Cells[i, 4].Value = db.Rows[i - 2]["MemBirthday"];
                    worksheet.Cells[i, 5].Value = db.Rows[i - 2]["MemPoint"];
                    worksheet.Cells[i, 6].Value = db.Rows[i - 2]["MemConsumeMoney"];
                    worksheet.Cells[i, 7].Value = db.Rows[i - 2]["ShopName"];
                }
                var data = package.GetAsByteArray();
                //儲存和歸來的Excel檔案作為一個ByteArray
                HttpResponse response = HttpContext.Current.Response;
                Response.Clear();

                //輸出標頭檔案　　
                Response.AddHeader("content-disposition", "attachment;  filename=會員資訊.xlsx");
                Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                Response.BinaryWrite(data);
                Response.Flush();
                Response.End();
                //package.Save();//這個方法是直接下載到本地
            }
        }