In this article, a method of single-event burnout (SEB) hardening at high linear energy transfer (LET) value range is proposed and investigated by the 2-D numerical simulations. The improved MOSFET using this method and the conventional MOSFET are analyzed and compared to evaluate the effectiveness of this method. Simulation results show that, compared with the conventional MOSFET, the improved MOSFET using this method can effectively and quickly reduce the internal high electric field, thereby reducing the temperature. Under the condition of a LET value of 0.5 pC/<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> and a drain voltage of 1200 V, the maximum drain current is 0.168 A, and the maximum global device temperature is 1724 K, which is much lower than the melting down temperature of silicon carbide (SiC) (3100 K). The hardening method in this article can be applied to different breakdown voltages by adjusting structure parameters.