As the hill gap is required to increase by ~1 cm due to the installation of RF, centering coils, beam diagnostics and etc., several adjusted geometries of the main magnet are investigated numerically and the new magnetic field distribution is provided for As the hill gap is required to increase by ~ 1 cm due to the installation of RF, centering coils, beam diagnostics and etc., several adjusted geometries of the main magnet are investigated numerically and the new magnetic field distribution is provided for