以下是先手動建立一個DataTable,利用NPOI匯出Excel,在向Sheet匯入資料後可以設定樣式

 static void Main()
        {
            DataTableToExcel(GetDt());
        }
        public static void DataTableToExcel(DataTable dt)
        {
            IWorkbook workbook = null;
            IRow row = null;
            ISheet sheet = null
 
;
            ICell cell = null;
            FileStream fs = null;

            if (dt != null && dt.Rows.Count > 0)
            {
                workbook = new XSSFWorkbook();
                sheet = workbook.CreateSheet("Sheet0");
                int rowCount = dt.Rows.Count;
                
 
int columnCount = dt.Columns.Count;
                //設定列頭  
                row = sheet.CreateRow(0);
                for (int c = 0; c < columnCount; c++)
                {
                    cell = row.CreateCell(c);
                    cell.SetCellValue(dt.Columns[c].ColumnName);
                }
                
 
//設定每行每列的單元格,  
                for (int i = 0; i < rowCount; i++)
                {

                    row = sheet.CreateRow(i + 1);
                    for (int j = 0; j < columnCount; j++)
                    {
                        cell = row.CreateCell(j);
                        cell.SetCellValue(dt.Rows[i][j].ToString());
                    }
                }
                //背景色
                XSSFCellStyle cellStyle = (XSSFCellStyle)workbook.CreateCellStyle();
                cellStyle.FillPattern = FillPattern.SolidForeground;
                cellStyle.FillBackgroundColor = IndexedColors.LightGreen.Index;
                cellStyle.FillForegroundColor = IndexedColors.LightGreen.Index;
                sheet.GetRow(1).GetCell(3).CellStyle = cellStyle;

                //字型顏色
                IFont font = workbook.CreateFont();//建立一個字型並且設定顏色
                font.Color = IndexedColors.Red.Index;
                ICellStyle style = workbook.CreateCellStyle();
                style.SetFont(font);
                sheet.GetRow(2).GetCell(3).CellStyle = style;


                using (fs = File.OpenWrite(@"D:\a.xlsx"))
                {
                    workbook.Write(fs);//向開啟的這個xls檔案中寫入資料  
                }
                System.Diagnostics.Process.Start(@"D:\a.xlsx");
            }
        }

        static DataTable GetDt()
        {
            DataTable tblDatas = new DataTable("Datas");
            DataColumn dc = null;
            dc = tblDatas.Columns.Add("ID", Type.GetType("System.Int32"));
            dc.AutoIncrement = true;//自動增加
            dc.AutoIncrementSeed = 1;//起始為1
            dc.AutoIncrementStep = 1;//步長為1
            dc.AllowDBNull = false;//

            dc = tblDatas.Columns.Add("Product", Type.GetType("System.String"));
            dc = tblDatas.Columns.Add("Version", Type.GetType("System.String"));
            dc = tblDatas.Columns.Add("Description", Type.GetType("System.String"));

            DataRow newRow;
            newRow = tblDatas.NewRow();
            newRow["Product"] = "VS";
            newRow["Version"] = "2022";
            newRow["Description"] = "又快又好用";
            tblDatas.Rows.Add(newRow);

            newRow = tblDatas.NewRow();
            newRow["Product"] = "VS";
            newRow["Version"] = "2019";
            newRow["Description"] = "好用穩定";
            tblDatas.Rows.Add(newRow);
            return tblDatas;
        }

主要程式碼：

//背景色
                XSSFCellStyle cellStyle = (XSSFCellStyle)workbook.CreateCellStyle();
                cellStyle.FillPattern = FillPattern.SolidForeground;
                cellStyle.FillBackgroundColor = IndexedColors.LightGreen.Index;
                cellStyle.FillForegroundColor = IndexedColors.LightGreen.Index;
                sheet.GetRow(1).GetCell(3).CellStyle = cellStyle;

                //字型顏色
                IFont font = workbook.CreateFont();//建立一個字型並且設定顏色
                font.Color = IndexedColors.Red.Index;
                ICellStyle style = workbook.CreateCellStyle();
                style.SetFont(font);
                sheet.GetRow(2).GetCell(3).CellStyle = style;

結果：