可是使用NPOI插件，在导出前把图片转成字符流添加到excel指定位置输出。

private static void setPic(HSSFWorkbook workbook, HSSFPatriarch patriarch, string path, ISheet sheet, int rowline, int col)
        {
            try
            {
                if (string.IsNullOrEmpty(path)) return;
                var dPath = AppDomain.CurrentDomain.BaseDirectory + path.Replace("网络路径", "").Replace(@"/", @"\");
                byte[] bytes = System.IO.File.ReadAllBytes(dPath);
                int pictureIdx = workbook.AddPicture(bytes, PictureType.JPEG);
                // 插图片的位置 
                HSSFClientAnchor anchor = new HSSFClientAnchor(70, 10, 0, 0, col, rowline, col + 1, rowline + 1);
                //把图片插到相应的位置
                HSSFPicture pict = (HSSFPicture)patriarch.CreatePicture(anchor, pictureIdx);
            }
            catch (Exception)
            {
            }
           
        }