The study investigated the impact of leakage degradation caused by heavy ions on the gate reliability of 1 200 V SiC MOSFETs. The results showed that under Ta ion irradiation, when V_DS was between 150 V and 200 V, the device's leakage current increased from nanoamperes to microamperes. Emission Microscope (EMMI) analysis revealed that the damage was primarily concentrated in the main junction region of the device. After 168 hours of testing at a 20 V gate voltage, the gate leakage current of the degraded device increased from a few microamperes to hundreds of microamperes. However, the maximum transconductance and transfer characteristics did not change significantly. The experiment also confirmed that under negative gate voltage irradiation conditions, the device gate was more susceptible to leakage. In summary, this study provides new insights into the evaluation of gate reliability and the enhancement of radiation hardness for SiC MOSFETs after irradiation, offering valuable perspectives for simulating heavy ion single-particle effects relevant to both space and ground environments.