EPPLUS教程

static string path= HttpContext.Current.Server.MapPath("..//Rpt//Template/test.xlsx");
ExcelPackage excelPackage = null;
ExcelWorksheet excelWorksheet = null;
FileInfo fileInfo = new FileInfo(path);
excelPackage = new ExcelPackage(fileInfo);

//sheet从1开始
excelWorksheet = excelPackage.Workbook.Worksheets[1]
ExcelRange cells = excelWorksheet.Cells;
cells.Style.Font.Size = 10;//字体大小
cells.Style.Font.Name = "宋体";//文字字体 
//                            //单元格样式
cells.Style.HorizontalAlignment = ExcelHorizontalAlignment.Left;//水平居中
cells.Style.VerticalAlignment = ExcelVerticalAlignment.Center;

cells.Style.WrapText = true;//单元格内容自动换行

//cells从11开始
cells[1, 2].Value = "11";
cells[2, 2].Value = "22";