一.使用OleDb,这个法子好像不大好使.容易读错.
引用System.Data.OleDb;

    /**//// <summary>
        /// 返回Excel数据源
        /// </summary>
        /// <param name="filename">文件路径</param>
        /// <returns></returns>
    static public DataSet ExcelToDataSet(string filename)
    {
        DataSet ds;
        string strCon = "Provider=Microsoft.Jet.OLEDB.4.0;" +
                        "Extended Properties=Excel 8.0;" +
                        "data source=" + filename;
        OleDbConnection myConn = new OleDbConnection(strCon);
        string strCom = " SELECT * FROM [Sheet1$]";
        myConn.Open();
        OleDbDataAdapter myCommand = new OleDbDataAdapter(strCom, myConn);
        ds = new DataSet();
        myCommand.Fill(ds);
        myConn.Close();
        return ds;
    }
二.使用com.
导入Microsoft.Excel
使用命名空间
using Excel= Microsoft.Office.Interop.Excel;
using System.Diagnostics;

public  class ExcelHelper
    {
      private Excel._Application excelApp;
      private string fileName=string.Empty;
      private Excel.WorkbookClass wbclass;
      public ExcelHelper(string _filename)
      {
          excelApp = new Excel.Application();
          object   objOpt   =   System.Reflection.Missing.Value;
          wbclass = (Excel.WorkbookClass)excelApp.Workbooks.Open(_filename, objOpt, false, objOpt, objOpt, objOpt, true, objOpt, objOpt, true, objOpt, objOpt, objOpt, objOpt, objOpt);
      }
      /**//// <summary>
      /// 所有sheet的名称列表
      /// </summary>
      /// <returns></returns>
      public List<string> GetSheetNames()
      {
          List<string> list = new List<string>();
          Excel.Sheets sheets = wbclass.Worksheets;
          string sheetNams = string.Empty;
          foreach (Excel.Worksheet sheet in sheets)
          {
            list.Add(sheet.Name);
          }
          return list;
      }
      public Excel.Worksheet GetWorksheetByName(string name)
      {
          Excel.Worksheet sheet=null;
          Excel.Sheets sheets= wbclass.Worksheets;
          foreach (Excel.Worksheet s in sheets)
          {
              if (s.Name == name)
              {
                  sheet = s;
                  break;
              }
          }
          return sheet;
      }
      /**//// <summary>
      ///
      /// </summary>
      /// <param name="sheetName">sheet名称</param>
      /// <returns></returns>
      public Array GetContent(string sheetName)
      {
          Excel.Worksheet sheet = GetWorksheetByName(sheetName);
          //获取A1 到AM24范围的单元格
          Excel.Range rang = sheet.get_Range("A1", "AM24");
          //读一个单元格内容
          //sheet.get_Range("A1", Type.Missing);
        //不为空的区域,列,行数目
       //   int l = sheet.UsedRange.Columns.Count;
         // int w = sheet.UsedRange.Rows.Count;
        //  object[,] dell = sheet.UsedRange.get_Value(Missing.Value) as object[,];
          System.Array values = (Array)rang.Cells.Value2;
          return values;
      }

      public void Close()
      {
          excelApp.Quit();
          excelApp = null;
      }
  
    }