1 下载Epplus最新版： http://epplus.codeplex.com/

2 在项目中添加引用 EEPULS.dll（测试环境Win7+V2010旗舰）

3  添加using引用

4 read Excel文件

private void button2_Click(object sender, EventArgs e)
    {
      string pfilePath = "";
      OpenFileDialog ofd = new OpenFileDialog();
      ofd.Filter = "*.xls|*.xlsx";
      if (ofd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
      {
        pfilePath = ofd.FileName;
      }
      if (string.IsNullOrEmpty(pfilePath))
      {
        MessageBox.Show("没有选中文件");
        return;
      }

      FileInfo existingFile = new FileInfo(pfilePath);
      try
      {
        ExcelPackage package = new ExcelPackage(existingFile);
        int vSheetCount = package.Workbook.Worksheets.Count; //获取总Sheet页

        ExcelWorksheet worksheet = package.Workbook.Worksheets[1];//选定 指定页

        int maxColumnNum = worksheet.Dimension.End.Column;//最大列
        int minColumnNum = worksheet.Dimension.Start.Column;//最小列

        int maxRowNum = worksheet.Dimension.End.Row;//最小行
        int minRowNum = worksheet.Dimension.Start.Row;//最大行

        DataTable vTable = new DataTable();
        DataColumn vC;
        for (int j = 1; j <= maxColumnNum; j++)
        {
          vC = new DataColumn("A_" + j, typeof(string));
          vTable.Columns.Add(vC);
        }
        if (maxRowNum > 200)
        {
          maxRowNum = 200;
        }
        for (int n = 1; n <= maxRowNum; n++)
        {
          DataRow vRow = vTable.NewRow();
          for (int m = 1; m <= maxColumnNum; m++)
          {
            vRow[m - 1] = worksheet.Cells[n, m].Value;
          }
          vTable.Rows.Add(vRow);
        }
        this.dataGridView1.DataSource = vTable;
      }
      catch (Exception vErr)
      {
        MessageBox.Show(vErr.Message);
      }
    }

5 write Excel文件

private void button1_Click(object sender, EventArgs e)
        {
          
     OfficeOpenXml.ExcelPackage ep = new OfficeOpenXml.ExcelPackage();
     OfficeOpenXml.ExcelWorkbook wb = ep.Workbook;
     OfficeOpenXml.ExcelWorksheet ws = wb.Worksheets.Add("我的工作表");
     //配置文件属性  
     wb.Properties.Category = "类别";
     wb.Properties.Author = "作者";
     wb.Properties.Comments = "备注";
     wb.Properties.Company = "公司";
     wb.Properties.Keywords = "关键字";
     wb.Properties.Manager = "管理者";
     wb.Properties.Status = "内容状态";
     wb.Properties.Subject = "主题";
     wb.Properties.Title = "标题";
     wb.Properties.LastModifiedBy = "最后一次保存者";
     //写数据  
     ws.Cells[1, 1].Value = "Hello";

     ws.Column(1).Width=40;//修改列宽  
     ws.Cells["B1"].Value = "World";
     ws.Cells[3, 3, 3, 5].Merge = true;
     ws.Cells[3, 3].Value = "Cells[3, 3, 3, 5]合并";
     ws.Cells["A4:D5"].Merge = true;
     ws.Cells["A4"].Value = "Cells[\"A4:D5\"]合并";

     SaveFileDialog sfd = new SaveFileDialog();
     sfd.Filter = "*.xls|*.xlsx";
     if (sfd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
     {
         FileInfo file = new FileInfo(sfd.FileName); 
         ep.File = file;
         ep.Save();
         MessageBox.Show("保存成功");
     }
     else
     {
         MessageBox.Show("取消保存");
     }
        }

上述代码大部分来源网络，只进行过小改动，下面是原文和资料地址：

http://blog.csdn.net/jimmy2248/article/details/8363697

http://blog.csdn.net/zhoufoxcn/article/details/14112473

http://www.cnblogs.com/liudeyun/p/3535740.html

http://blog.163.com/china__xuhua/blog/static/19972316920136335721285/