The invention provides a low-power-consumption high-reliability semi-wrapped trench gate silicon carbide MOSFET device and a preparation method thereof. The low-power-consumption high-reliability semi-wrapped trench gate silicon carbide MOSFET device comprises an N-type substrate, an N-type epitaxial layer, a first P-body region, a first P + contact region, a first N + contact region, a second P-body region, a second P + contact region, a second N + contact region, a gate medium, a trench gate, an auxiliary trench gate, a source electrode and a drain electrode. Compared with a traditional half-wrapped trench gate silicon carbide MOSFET, the gate dielectric is protected by forming the second P-body region at the bottom of the trench, the reliability of the gate dielectric of the device is enhanced, a part of gate-drain capacitance is shielded, the switching loss of the device is reduced on the basis of not sacrificing the conduction capability of the original trench MOSFET, and when the device is short-circuited, the drain voltage is relatively large, so that the reliability of the device is improved. And at the moment, the JFET region between the second P-body region and the first P + contact region is pinched off, so that the saturation current of the device is reduced, and the short-circuit capability of the device is improved.