The invention relates to a silicon carbide MOSFET device with a unilateral masking layer. The silicon carbide MOSFET device comprises a drain electrode, an N-type doping substrate layer, an N-type drift region and a P-type base region which are arranged in order from bottom to top; the P-type base region is provided with a P-type source region and an N-type source region; the P-type base region isinternally provided with a groove-gate structure, the bottom portion of the groove-gate structure is extended into the N-type drift region, the top portion of the groove-gate structure is extended out of the upper surface of the P-type base region; the lower portion of the groove-gate structure is provided with a masking layer, the upper surface of the marking layer is in contact with the lower surface of the groove-gate structure, and the marking layer only covers part of the lower surface of the groove-gate structure; the P-type source region and the N-type source regions are provided withsource electrodes; and the groove-gate structure is provided with a gate electrode. According to the silicon carbide MOSFET device, the marking layer is added at the bottom portion of the groove-gatestructure to improve the breakdown voltage of the device.