第一种办法：直接在button的Click事件中写代码进行导出：

        private void button6_Click(object sender, EventArgs e)
        {
            SaveFileDialog saveFileDialog = new SaveFileDialog();
            saveFileDialog.Filter = "Excel files (*.xls)|*.xls";
            saveFileDialog.FilterIndex = 0;
            saveFileDialog.RestoreDirectory = true;
            saveFileDialog.CreatePrompt = true;
            saveFileDialog.Title = "导出Excel文件到";

            saveFileDialog.ShowDialog();
            try
            {
                Stream myStream;
                myStream = saveFileDialog.OpenFile();
                StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding("gb2312"));
                string str = "";

                //写标题  
                for (int i = 0; i < dataGridView1.ColumnCount; i++)
                {
                    if (i > 0)
                    {
                        str += "\t";
                    }
                    str +=dataGridView1.Columns[i].HeaderText;
                }

                sw.WriteLine(str);
                //写内容 
                for (int j = 0; j < dataGridView1.Rows.Count; j++)
                {
                    string tempStr = "";
                    for (int k = 0; k < dataGridView1.Columns.Count; k++)
                    {
                        if (k > 0)
                        {
                            tempStr += "\t";
                        }
                        tempStr +="'"+dataGridView1.Rows[j].Cells[k].Value.ToString();
                    }
                    sw.WriteLine(tempStr);
                }
                MessageBox.Show("导出成功", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                sw.Close();
                myStream.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
            finally
            {
                //sw.Close();
                //myStream.Close();
            }
        }

这种方法速度较快。

第二种办法：通过编写公共类，然后进行调用。

类

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Windows.Forms;
using System.Reflection;
using System.Runtime.InteropServices;
using Microsoft.Office.Interop.Excel;

namespace WindowsFormsApplication3
{
    class ToExcel
    {
        public static void DataGridViewToExcel(DataGridView dgv, string title)
        {
            int rowCount = dgv.RowCount;
            int columnCount = 0;
            foreach (DataGridViewColumn dHeader in dgv.Columns)
            {
                if (dHeader.Visible == true)
                    columnCount++;
            }
            Microsoft.Office.Interop.Excel.Application exc = new  Microsoft.Office.Interop.Excel.Application();
 
            if (exc == null)
            {
                throw new Exception("Excel无法启动");
            }
            //
 
            //
            Workbooks workbooks = exc.Workbooks;
            //
            _Workbook workbook = workbooks.Add(XlWBATemplate.xlWBATWorksheet);
            //
            Sheets sheets = exc.Sheets;
            _Worksheet worksheet = (_Worksheet)sheets[1];
            if (worksheet == null)
            {
                throw new Exception("Worksheet error");
            }
 
            Range r = worksheet.get_Range(exc.Cells[1, 1], exc.Cells[1, columnCount]);
            exc.Visible = false;
            r.MergeCells = true;
            if (r == null)
            {
                MessageBox.Show("Range无法启动");
                throw new Exception("Range error");
            }
            //以上是一些例行的初始化工作,下面进行具体的信息填充
            //标题
            exc.ActiveCell.FormulaR1C1 = title;
            exc.ActiveCell.Font.Size = 12;
            exc.ActiveCell.Font.Bold = true;
 
            //列头
            int ColIndex = 1;
            foreach (DataGridViewColumn dHeader in dgv.Columns)
            {
                if (dHeader.Visible == true)
                    worksheet.Cells[2, ColIndex++] = dHeader.HeaderText;
            }
            //填充单元格
            ColIndex = 0;
            foreach (DataGridViewColumn col in dgv.Columns)
            {
                if (col.Visible == true)
                {
                    ColIndex++;
                    for (int i = 0; i < rowCount; i++)
                    {
                        if (dgv.Rows[i].Cells[col.Index].Value == null)
                            continue;
                        worksheet.Cells[i + 3, ColIndex] = "'"+dgv.Rows[i].Cells[col.Index].Value.ToString();
 
                    }
                }
            }
 
 
            exc.Cells.EntireColumn.AutoFit();
            exc.Cells.VerticalAlignment = Microsoft.Office.Interop.Excel.Constants.xlCenter;
            exc.Cells.HorizontalAlignment = Microsoft.Office.Interop.Excel.Constants.xlCenter;
            exc.Visible = true;
        }
    }
    
}

调用代码：

        private void button4_Click(object sender, EventArgs e)
        {
            if (dataGridView1.RowCount == 0)
            {
                return;
            }
            else
            {
                ToExcel.DataGridViewToExcel(dataGridView1, "学生表");
            }
        }

这种办法可以添加上表头

第三种办法：添加一个公共类，然后进行调用，这种调用会显示存储在哪个位置，然后进行保存。

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication3
{
    class DataGridToExcel
    {
        public static bool DataGridviewShowToExcel(DataGridView dgv)
        {
            if (dgv.Rows.Count == 0)
            {
                MessageBox.Show("数据源为空，导出无效");
                return false;
            }
            //建立Excel对象 
            Microsoft.Office.Interop.Excel.Application excel =
            new Microsoft.Office.Interop.Excel.ApplicationClass();

            excel.Application.Workbooks.Add(true);
            excel.Visible = true;
            //生成字段名称 
            for (int i = 0; i < dgv.ColumnCount; i++)
            {
                excel.Cells[1, i + 1] = dgv.Columns[i].HeaderText;
            }
            //填充数据 
            for (int i = 0; i < dgv.RowCount - 1; i++)
            {
                for (int j = 0; j < dgv.ColumnCount; j++)
                {
                    excel.Cells[i + 2, j + 1] = "'" + dgv[j, i].Value.ToString();
                }
            }
            return true;
        }
    }
}

这种代码比较简单，导出的列默认都设置为了文本格式，避免转换保存出现数据错误。