借用NPOI来实现，要在同一Excel文件中创建多个sheet，只需要在同一个workbook中创建多个sheet即可。要注意的是，sheet的名字一定不能重复。下面是实现的代码：

private void buttonTest_Click(object sender, EventArgs e)

{

HSSFWorkbook workBook = new HSSFWorkbook();

//ISheet sheetA = workBook.CreateSheet("sheetA");

//ISheet sheetB = workBook.CreateSheet("sheetB");

createSheet(workBook,"SheetA");

createSheet(workBook,"SheetB");

createSheet(workBook,"SheetC");

string path = Application.StartupPath + @"\test.xls";

if (File.Exists(path))

{

File.Delete(path);

}

using (FileStream file = new FileStream(path, FileMode.Create))

{

workBook.Write(file);　　//创建Excel文件。

file.Close();

}

MessageBox.Show("OK");

}

private ISheet createSheet(HSSFWorkbook workBook, string sheetName)

{

ISheet sheet = workBook.CreateSheet(sheetName);

IRow RowHead = sheet.CreateRow(0);

for (int iColumnIndex = 0; iColumnIndex < 10; iColumnIndex++)

{

RowHead.CreateCell(iColumnIndex).SetCellValue(Guid.NewGuid().ToString());

}

for (int iRowIndex = 0; iRowIndex < 20; iRowIndex++)

{

IRow RowBody = sheet.CreateRow(iRowIndex + 1);

for (int iColumnIndex = 0; iColumnIndex < 10; iColumnIndex++)

{

RowBody.CreateCell(iColumnIndex).SetCellValue(DateTime.Now.Millisecond);

sheet.AutoSizeColumn(iColumnIndex);

}

}

return sheet;

}