public void ExportDataToExcel()
        {
            var workbook = new HSSFWorkbook();

            var sheet = workbook.CreateSheet("測試NPOI");
            sheet.DefaultColumnWidth = 20;
            sheet.ForceFormulaRecalculation = true;

            var headFont = workbook.CreateFont();
            headFont.IsBold 
 
= true;

            //標題列樣式
            var headStyle = workbook.CreateCellStyle();
            headStyle.Alignment = HorizontalAlignment.Center;
            headStyle.BorderBottom = BorderStyle.Thin;
            headStyle.BorderLeft = BorderStyle.Thin;
            headStyle.BorderRight = BorderStyle.Thin;
            headStyle.BorderTop 
 
= BorderStyle.Thin;
            headStyle.SetFont(headFont);
            
            var rowIndex = 0;
            var row = sheet.CreateRow(rowIndex);
            var cell = row.CreateCell(0);
            cell.SetCellValue("姓名");
            cell.CellStyle = headStyle;

            cell = row.CreateCell(1
 
);
            cell.SetCellValue("年齡");
            cell.CellStyle = headStyle;

            //單元格邊框
            var cellStyle=workbook.CreateCellStyle();
            cellStyle.BorderBottom = BorderStyle.Thin;
            cellStyle.BorderLeft = BorderStyle.Thin;
            cellStyle.BorderRight = BorderStyle.Thin;
            cellStyle.BorderTop = BorderStyle.Thin;
            for (var i = 1; i < 6; i++)
            {
                row = sheet.CreateRow(i);
                cell = row.CreateCell(0);
                cell.SetCellValue($"測試{i}");
                cell.CellStyle = cellStyle;

                cell = row.CreateCell(1);
                cell.SetCellValue(i);
                cell.CellStyle = cellStyle;
            }

            //公式計算
            row = sheet.CreateRow(7);
            cell = row.CreateCell(3);
            cell.SetCellValue(100);

            cell = row.CreateCell(4);
            cell.SetCellValue(200);

            cell = row.CreateCell(5);
            cell.CellFormula = "D8+E8";

            string Path = @"D:\AA\導出\";
            //Excel的路徑及名稱
            string excelPath = Path + "AA1.xls";
            FileStream fileStream = new FileStream(excelPath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
            if (!workbook.IsWriteProtected)
            {
                workbook.Write(fileStream);
            }

            fileStream.Close();
        }

NuGet安裝NPOI版本 2.4.1

.net core 實現npoi導出