Single Event Gate Rupture(SEGR) is one of the most severe problems that SiC MOSFETs experience in the space radiation environment. The influence of drain bias (VDS) and gate bias (VGS) on Single Event Gate Rupture was explored in this work using the fluctuation of leakage current when the device was irradiated at various biases. The source of leakage current is isolated and determined through testing, and the influence mechanisms of VGS and VDS effects on SEGR are further explored using TCAD simulation. The investigation demonstrates that while the drain bias can indirectly enhance the potential of SiC-side oxide, the gate bias can directly alter the potential of metal-side oxide during heavy ion irradiation. When gate bias and drain bias are combined, a strong electric field is generated in the gate oxide, resulting in SEGR in SiC MOSFETs. SEGR effect is a significant issue for SiC MOSFETs.