1. 新建一个.net core 3.0控制台应用程序，添加引用DotNetCore.NPOI， Version: 1.2.2

2. 创建一个.xlsx文件

class Program
    {
        static void Main(string[] args)
        {
            var workbook = new XSSFWorkbook();

            var sheet = workbook.CreateSheet("TestSheet");

            sheet.CreateRow(0).CreateCell(0).SetCellValue("Hello World");

            var path = @"D:\Test\Test.xlsx";
            using (var stream = new FileStream(path, FileMode.Create, FileAccess.Write))
            {
                workbook.Write(stream);            
            }
        }
    }

3. 创建一个.xls文件

class Program
    {
        static void Main(string[] args)
        {
            var workbook = new HSSFWorkbook();

            var sheet = workbook.CreateSheet("TestSheet");

            sheet.CreateRow(0).CreateCell(0).SetCellValue("Hello World");

            var path = @"D:\Test\Test.xls";
            using (var stream = new FileStream(path, FileMode.Create, FileAccess.Write))
            {
                workbook.Write(stream);            
            }
        }
    }

Result：

在引入NPOI的同时，还引入了System.Drawing.Common.dll, Microsoft.Win32.SystemEvents.dll, ISCharpCode.SHarpZipLib.dll.

DotNetCore.NPOI的依赖：

ICSharpCode.SharpZipLib, Version=1.2.0.246, Culture=neutral, PublicKeyToken=1b03e6acf1164f73
mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51
System.Drawing.Common, Version=4.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51
System.Text.Encoding.CodePages, Version=4.1.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a