FileStream fs = File.Open("文件名.扩展名", FileMode.OpenOrCreate,FileAccess.Read);
byte[] bt=new byte[fs.Length];
fs.Read(bt, 0, bt.Length);
string text = Encoding.Default.GetString(bt);
fs.Close();
datagridview1.Rows.Add();
datagridview1.Rows[0].Cells[0].value=text;
可以用文件流啊 FileStream