参考：

Visual Studio 进行Excel相关开发，Microsoft.Office.Interop.Excel.dll库
https://www.cnblogs.com/arxive/p/5786241.html

说明：

Microsoft.Office.Interop.Excel.dll 在VS中已自带，不需要再在网上下载。
引用方法：引用--扩展集，VS已自带Excel的dll库。
路径参考如下：D:\Program Files (x86)\Microsoft Visual Studio 12.0\Visual Studio Tools for Office\PIA\Office14\Microsoft.Office.Interop.Excel.dll）

导出到Excel的方法：---测试ok！

private void ExportExcel(DataTable dt)
{
if (null == dt || dt.Rows.Count <= 0) return;

string savePath = string.Empty;
FolderBrowserDialog dialog = new FolderBrowserDialog();
dialog.Description = "请选择保存路径";
//dialog.RootFolder = Environment.SpecialFolder.Desktop;
if (dialog.ShowDialog() == DialogResult.OK)
{
savePath = dialog.SelectedPath + "\\" + DateTime.Now.ToString("yyyyMMddHHmmss") + ".xlsx";
}
else
{
return;
}

//需要添加 Microsoft.Office.Interop.Excel引用
Microsoft.Office.Interop.Excel.Application app = new Microsoft.Office.Interop.Excel.Application();
if (null == app)
{
MessageBox.Show("缺少Excel组件！");
return;
}

app.Visible = false;
app.UserControl = true;

Microsoft.Office.Interop.Excel.Workbook workbook = app.Workbooks.Add(Microsoft.Office.Interop.Excel.XlWBATemplate.xlWBATWorksheet);
Microsoft.Office.Interop.Excel.Worksheet worksheet = (Microsoft.Office.Interop.Excel.Worksheet)workbook.Worksheets[1];
worksheet.Name = "商品数据"; // 修改sheet名称
//Microsoft.Office.Interop.Excel.Range range;
//long totalCount = dt.Rows.Count;
//long rowRead = 0;
//float percent = 0; // 导出进度

// 保存列名，Excel的索引从1开始
for (int i = 0; i < dt.Columns.Count; i++)
{
worksheet.Cells[1, i + 1] = dt.Columns[i].ColumnName;
// 标题设置
//range = (Microsoft.Office.Interop.Excel.Range)worksheet.Cells[1, i + 1];
//range.Interior.ColorIndex = 15; // 背景色
//range.Font.Bold = true; // 粗体
}
// 保存数据
for (int r = 0; r < dt.Rows.Count; r++)
{
for (int i = 0; i < dt.Columns.Count; i++)
{
worksheet.Cells[r + 2, i + 1] = dt.Rows[r][i].ToString();
}
//rowRead++;
//percent = ((float)(100 * rowRead)) / totalCount; // 当前进度
}

// 合计：
//worksheet.Cells[DT.Rows.Count + 2, 1] = "合计";
//worksheet.Cells[DT.Rows.Count + 2, 4] = DT.Compute("sum(Quantity)", ""); // DataTable筛选条件
//worksheet.Cells[DT.Rows.Count + 2, 6] = DT.Compute("sum(TotalAmt)", "");

//调整Excel的样式。
//Microsoft.Office.Interop.Excel.Range rg = worksheet.Cells.get_Range("A3", worksheet.Cells[rowCount + 2, 32]);
//rg.Borders.LineStyle = 1; //单元格加边框
//worksheet.Columns.AutoFit(); //自动调整列宽

//隐藏某一行
//选中部分单元格，把选中的单元格所在的行的Hidden属性设为true
//worksheet.get_Range(app.Cells[2, 1], app.Cells[2, 32]).EntireRow.Hidden = true;

//删除某一行
// worksheet.get_Range(app.Cells[2, 1], app.Cells[2, 32]).EntireRow.Delete(Microsoft.Office.Interop.Excel.XlDirection.xlUp);

//string savePath = "导出数据.xls";
//string savePath = System.Windows.Forms.Application.StartupPath + "\\"+DateTime.Now.ToString("yyyyMMddHHmmss") + ".xlsx";

workbook.SaveAs(savePath);

// 释放资源
workbook.Close();
workbook = null;
app.Quit();
app = null;

MessageBox.Show("导出数据成功！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
}