string _excelconnstr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + Server.MapPath(@"ExportInExcel/" + _newfilename + ".xls") + ";Extended Properties='Excel 8.0;HDR=Yes;IMEX=1;'";    

OleDbConnection oledbconn = new OleDbConnection(_excelconnstr);
oledbconn.Open();
OleDbCommand command = new OleDbCommand("SELECT * FROM [Sheet1$]", oledbconn);
OleDbDataAdapter adp = new OleDbDataAdapter(command);
adp.Fill(ds);
oledbconn.Close();

this.GridView1.DataSource = ds.Tables[0];
this.GridView1.DataBind();