方法1:调用com组件,导出access数据到Excel,就是直接调用access的导出功能,此方法速度超级快
using Access;

Access.ApplicationClass oAccess = new Access.ApplicationClass();
oAccess.Visible = false;
try
{
//ACCESS9:
oAccess.OpenCurrentDatabase("d:\\wcf.mdb",false,"");
//导出到excel
oAccess.DoCmd.TransferSpreadsheet(Access.AcDataTransferType.acExport,Access.AcSpreadSheetType.acSpreadsheetTypeExcel9,"工作表名","d:\\wcf.xls",true,null,null);
//导入txt
//oAccess.DoCmd.TransferText(Access.AcTextTransferType.acExportDelim,"","Enterprise","d:\\wcf.txt",true,"",0);
oAccess.CloseCurrentDatabase();
oAccess.DoCmd.Quit(Access.AcQuitOption.acQuitSaveNone);
System.Runtime.InteropServices.Marshal.ReleaseComObject (oAccess);
oAccess = null;
MessageBox.Show("导入成功");
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
finally
{
GC.Collect();
}
方法2：此方法速度也是超级快，只不过导出的格式非标准的Excel格式，默认工作表名与文件名相同
string FileName="d:\\abc.xls";
System.Data.DataTable dt=new System.Data.DataTable();
FileStream objFileStream;
StreamWriter objStreamWriter;
string strLine="";
objFileStream = new FileStream(FileName,FileMode.OpenOrCreate,FileAccess.Write);
objStreamWriter = new StreamWriter(objFileStream,System.Text.Encoding.Unicode);

for(int i=0;i<dt.Columns.Count;i++)
{
strLine=strLine+dt.Columns[i].ColumnName.ToString()+Convert.ToChar(9);
}
objStreamWriter.WriteLine(strLine);
strLine="";

for(int i=0;i<dt.Rows.Count;i++)
{
strLine=strLine+(i+1)+Convert.ToChar(9);
for(int j=1;j<dt.Columns.Count;j++)
{
strLine=strLine+dt.Rows[i][j].ToString()+Convert.ToChar(9);
}
objStreamWriter.WriteLine(strLine);
strLine="";
}
objStreamWriter.Close();
objFileStream.Close();

方法3:用Ado.net 此方法速度较以上两个显得慢了一些，数据量越大越明显
int Id=0;
string Name="测试";
string FileName="d:\\abc.xls";
System.Data.DataTable dt=new System.Data.DataTable();
long totalCount=dt.Rows.Count;
long rowRead=0;
float percent=0;
OleDbParameter[] parm=new OleDbParameter[dt.Columns.Count];
string connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + FileName +";Extended Properties=Excel 8.0;";
OleDbConnection objConn = new OleDbConnection(connString);
OleDbCommand objCmd = new OleDbCommand();
objCmd.Connection = objConn;
objConn.Open();
//建立表结构
objCmd.CommandText = @"CREATE TABLE Sheet1(序号 Integer,名称 varchar)";
objCmd.ExecuteNonQuery();
//建立插入动作的Command
objCmd.CommandText = "INSERT INTO Sheet1("+Id+","+Name+")";
parm[0]=new OleDbParameter("@Id", OleDbType.Integer);
objCmd.Parameters.Add(parm[0]);
parm[1]=new OleDbParameter("@Company", OleDbType.VarChar);
objCmd.Parameters.Add(parm[1]);
//遍历DataTable将数据插入新建的Excel文件中
for(int i=0;i<dt.Rows.Count;i++)
{  
parm[0].Value=i+1;
for(int j=1;j<parm.Length;j++)
{
parm[j].Value =dt.Rows[i][j];
}
objCmd.ExecuteNonQuery();
rowRead++;
percent=((float)(100*rowRead))/totalCount;  
//this.FM.CaptionText.Text = "正在导出数据，已导出[" + percent.ToString("0.00") + "%]...";
if(i==dt.Rows.Count-1)
//this.FM.CaptionText.Text = "请稍后......";
System.Windows.Forms .Application.DoEvents();
}
objConn.Close();
//this.FM.CaptionText.Text = "";

方法4：此方法调用com组件，速度都慢于以上3个方法
using Excel;

System.Data.DataTable dt=new System.Data.DataTable();
string FileName="d:\\abc.xls";

long totalCount=dt.Rows.Count;
long rowRead=0;
float percent=0;
Excel.Application xlApp=null;
xlApp=new Excel.Application();
Excel.Workbooks workbooks=xlApp.Workbooks;
Excel.Workbook workbook=workbooks.Add(Excel.XlWBATemplate.xlWBATWorksheet);
Excel.Worksheet worksheet=(Excel.Worksheet)workbook.Worksheets[1];//取得sheet1
Excel.Range range;

//写入字段
for(int i=0;i<dt.Columns.Count;i++)
{
worksheet.Cells[1,i+1]=dt.Columns[i].ColumnName; 
range=(Excel.Range)worksheet.Cells[1,i+1];
}
for(int r=0;r<dt.Rows.Count;r++)
{
worksheet.Cells[r+2,1]=r+1;
for(int i=0;i<dt.Columns.Count;i++)
{
//worksheet.Cells[r+2,i+1]=dt.Rows[r][i];
if(i+1!=dt.Columns.Count)
worksheet.Cells[r+2,i+2]=dt.Rows[r][i+1];
}
rowRead++;
percent=((float)(100*rowRead))/totalCount;  
//this.FM.CaptionText.Text = "正在导出数据，已导出[" + percent.ToString("0.00") + "%]...";
System.Windows.Forms .Application.DoEvents();
}
range=worksheet.get_Range(worksheet.Cells[2,1],worksheet.Cells[dt.Rows.Count+2,dt.Columns.Count]);
workbook.Saved =true;
workbook.SaveCopyAs(FileName);
//this.FM.CaptionText.Text = "";

方法5：利用剪贴板 ,有人说此方法很快，但是我用时，这种方法最慢，请高手指点.
System.Data.DataTable dt=new System.Data.DataTable();
string filePath=@"d:\abc.xls";

object oMissing = System.Reflection.Missing.Value;
Excel.ApplicationClass xlApp = new Excel.ApplicationClass();
try
{
xlApp.Visible = false;
xlApp.DisplayAlerts = false;
Excel.Workbooks oBooks = xlApp.Workbooks;
Excel._Workbook xlWorkbook = null;
xlWorkbook = oBooks.Open(filePath,oMissing,oMissing,oMissing,oMissing,oMissing,oMissing,
oMissing,oMissing,oMissing,oMissing,oMissing,oMissing,oMissing,oMissing);

Excel.Worksheet xlWorksheet;
// 添加入一个新的Sheet页。
xlWorksheet = (Excel.Worksheet)xlWorkbook.Worksheets.Add(oMissing,oMissing,1,oMissing);
// 以TableName作为新加的Sheet页名。
xlWorksheet.Name ="企业名录";
// 取出这个DataTable中的所有值,暂存于stringBuffer中。
string stringBuffer = "";

for( int j=0; j<dt.Rows.Count; j++ )
{
for( int k=0; k<dt.Columns.Count; k++ )
{
stringBuffer += dt.Rows[j][k].ToString();
if( k < dt.Columns.Count - 1 )
stringBuffer += "\t";
}
stringBuffer += "\n";
}
// 利用系统剪切板
System.Windows.Forms.Clipboard.SetDataObject("");
// 将stringBuffer放入剪切板。
System.Windows.Forms.Clipboard.SetDataObject(stringBuffer);
// 选中这个sheet页中的第一个单元格
((Excel.Range)xlWorksheet.Cells[1,1]).Select();
// 粘贴！
xlWorksheet.Paste(oMissing,oMissing);
// 清空系统剪切板。
System.Windows.Forms.Clipboard.SetDataObject("");

// 保存并关闭这个工作簿。
xlWorkbook.Close( Excel.XlSaveAction.xlSaveChanges, oMissing, oMissing );
System.Runtime.InteropServices.Marshal.ReleaseComObject(xlWorkbook);
xlWorkbook = null;

这些方法都没有关闭Excel进程，这种资料很多，在此不多写了,希望这些能对一些人带来方便.