string path1;
this.openFileDialog1.Filter="excel文件(*.xls)|*.xls";
this.openFileDialog1.Title="打开excel文件";
this.openFileDialog1.ShowDialog();
path1=this.openFileDialog1.FileName;
object objMissing=System.Reflection.Missing.Value;
           //打开excel文件
Excel.ApplicationClass my=new Excel.ApplicationClass();
my.Visible=true;

Excel.Workbook mybook=my.Workbooks.Open(path1.Trim(),objMissing,objMissing, objMissing, 
objMissing, objMissing, objMissing, 
objMissing, objMissing, objMissing, 
objMissing, objMissing, objMissing);

Excel.Worksheet mysheet=(Excel.Worksheet)mybook.Worksheets.get_Item(1);
 //下面的语句得不到所要得结果，在VB中用mysheet.Cells（1,2）.value 来获得单元格得值，但在C#中没有该属性
this.textBox1.Text=mysheet.Cells[1,2].ToString();