The invention relates to a shield gate MOSFET device capable of reducing a terminal area and a preparation method therefor. A cellular region adopts a trench structure and is provided with a shield gate structure; a terminal trench is formed in a terminal protection region; the width of the terminal trench is higher than that of a cellular trench; a terminal trench insulation oxidization layer isarranged on the side wall and the bottom wall of the terminal trench, and the interior of the terminal trench provided with the terminal trench insulation oxidization layer is filled with terminal trench conductive polysilicon; the terminal trench adjacent to the cellular region is in contact with a second conductive type base region on the outer upward side of the side wall of the cellular trenchadjacent to the terminal protection region; source metal is arranged above a first conductive type drift region; and the source metal is in ohmic contact with the second conductive type base region,a first conductive type source region in the second conductive type base region and the terminal trench conductive polysilicon. The preparation method is compatible with the exiting process, the voltage withstand capability is improved effectively, the terminal area can be reduced, and safety and reliability are achieved.