导出为xls格式用HSSF，xlsx用XSSF。

1、类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using System.Text;
using NPOI.HSSF.UserModel;
using System.IO;
using NPOI.SS.UserModel;public class ExportExcel
{public void GridToExcel(string fileName, DataGridView dgv){if (dgv.Rows.Count == 0){return;}SaveFileDialog sfd = new SaveFileDialog();sfd.Filter = "Excel 2003格式|*.xls";sfd.FileName = fileName + DateTime.Now.ToString("yyyyMMddHHmmssms");if (sfd.ShowDialog() != DialogResult.OK){return;}HSSFWorkbook wb = new HSSFWorkbook();HSSFSheet sheet = (HSSFSheet)wb.CreateSheet(fileName);HSSFRow headRow = (HSSFRow)sheet.CreateRow(0);for (int i = 0; i < dgv.Columns.Count; i++){HSSFCell headCell = (HSSFCell)headRow.CreateCell(i, CellType.String);headCell.SetCellValue(dgv.Columns[i].HeaderText);}for (int i = 0; i < dgv.Rows.Count; i++){HSSFRow row = (HSSFRow)sheet.CreateRow(i + 1);for (int j = 0; j < dgv.Columns.Count; j++){HSSFCell cell = (HSSFCell)row.CreateCell(j);if (dgv.Rows[i].Cells[j].Value == null){cell.SetCellType(CellType.Blank);}else{if (dgv.Rows[i].Cells[j].ValueType.FullName.Contains("System.Int32")){cell.SetCellValue(Convert.ToInt32(dgv.Rows[i].Cells[j].Value));}else if (dgv.Rows[i].Cells[j].ValueType.FullName.Contains("System.String")){cell.SetCellValue(dgv.Rows[i].Cells[j].Value.ToString());}else if (dgv.Rows[i].Cells[j].ValueType.FullName.Contains("System.Single")){cell.SetCellValue(Convert.ToSingle(dgv.Rows[i].Cells[j].Value));}else if (dgv.Rows[i].Cells[j].ValueType.FullName.Contains("System.Double")){cell.SetCellValue(Convert.ToDouble(dgv.Rows[i].Cells[j].Value));}else if (dgv.Rows[i].Cells[j].ValueType.FullName.Contains("System.Decimal")){cell.SetCellValue(Convert.ToDouble(dgv.Rows[i].Cells[j].Value));}else if (dgv.Rows[i].Cells[j].ValueType.FullName.Contains("System.DateTime")){cell.SetCellValue(Convert.ToDateTime(dgv.Rows[i].Cells[j].Value).ToString("yyyy-MM-dd"));}}}}for (int i = 0; i < dgv.Columns.Count; i++){sheet.AutoSizeColumn(i);}using (FileStream fs = new FileStream(sfd.FileName, FileMode.Create)){wb.Write(fs);}MessageBox.Show("导出成功！","导出提示",MessageBoxButtons.OK,MessageBoxIcon.Information);} 
}

2、调用

using System;
using System.Data;
using System.IO;
using System.Text;
using System.Windows.Forms;
using NPOI.HPSF;
using NPOI.HSSF;
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;namespace NPOITest
{public partial class Form1 : Form{public Form1(){InitializeComponent();}private void btnDataSource_Click(object sender, EventArgs e){MyDBase DB = new MyDBase(".","GoodLuck","sa","123456");DataSet DS = DB.GetRecordset("select * from View_s");dataGridView1.DataSource = DS.Tables[0];DB.DBClose();}private void btnExport_Click(object sender, EventArgs e){ExportExcel Et = new ExportExcel();Et.GridToExcel("人员单位", dataGridView1);}private void btnClose_Click(object sender, EventArgs e){this.Close();}}
}