1.添加引用Microsoft.Office.Interop.Excel。

2.程序代码引用using Excel = Microsoft.Office.Interop.Excel;

3.控件事件代码:

       string fileName = "";
            string saveFileName = "";
            SaveFileDialog saveDialog = new SaveFileDialog();
            saveDialog.DefaultExt = "xls";
            saveDialog.Filter = "Excel文件|*.xls";
            saveDialog.FileName = fileName;
            saveDialog.ShowDialog();
            saveFileName = saveDialog.FileName; 
            if (saveFileName.IndexOf(":") < 0) return; //被点了取消
            Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();
            if (xlApp == null)
            {
                MessageBox.Show("无法创建Excel对象,您的电脑可能未安装Excel");
                return;
            }
            Microsoft.Office.Interop.Excel.Workbooks workbooks = xlApp.Workbooks;
            Microsoft.Office.Interop.Excel.Workbook workbook = workbooks.Add(Microsoft.Office.Interop.Excel.XlWBATemplate.xlWBATWorksheet);
            Microsoft.Office.Interop.Excel.Worksheet worksheet = (Microsoft.Office.Interop.Excel.Worksheet)workbook.Worksheets[1];//取得sheet1 
            //写入标题             
            for (int i = 0; i < dataGridView1.ColumnCount; i++)             
            {worksheet.Cells[1, i + 1] = dataGridView1.Columns[i].HeaderText;}
            //写入数值
            for (int r = 0; r < dataGridView1.Rows.Count; r++)
            { for (int i = 0; i < dataGridView1.ColumnCount; i++) 
            { 
                worksheet.Cells[r + 2, i + 1] = dataGridView1.Rows[r].Cells[i].Value;
            } 
                System.Windows.Forms.Application.DoEvents();
            }
            worksheet.Columns.EntireColumn.AutoFit();//列宽自适应
            MessageBox.Show(fileName + "资料保存成功", "提示", MessageBoxButtons.OK);
           if (saveFileName != "")
           {     
               try 
               {workbook.Saved = true;
                   workbook.SaveCopyAs(saveFileName);  //fileSaved = true;                 
               }                  
               catch (Exception ex)                 
               {//fileSaved = false;                      
                   MessageBox.Show("导出文件时出错,文件可能正被打开!\n" + ex.Message);                  
               }             
           }              
            xlApp.Quit();              
            GC.Collect();//强行销毁