string Con_Str = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + FullName + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=1\";";
OleDbConnection con = new OleDbConnection(Con_Str);
String qry = "SELECT * FROM [Sheet1$]";
OleDbDataAdapter odp = new OleDbDataAdapter(qry, con);
DataSet ds = new DataSet();
odp.Fill(ds);
Here you can make the insert option also.