Silicon carbide MOSFET has the advantages of low conduction loss, high opening speed and high temperature resistance. Its excellent breaking performance is an ideal choice for the development of low voltage DC circuit breakers. From the point of view of the current DC voltage level, the level of insulation and the safety of the circuit breaker, the operating voltage level of the circuit breaker is determined, and a simple low voltage DC circuit model is built to estimate the parameters of the components in the model. On the basis of this, the overvoltage of circuit breaker is calculated under two conditions of normal and short circuit, at the same time,according to the MOSFET parameters and characteristic curve of silicon carbide provided by the manufacturer,using the simulation software saber to establish the model, operating over voltage analysis. And the design of two kinds of overvoltage protection circuit to make SiC-MOSFET more secure and reliable work, the feasibility of silicon carbide MOSFET for 500V DC circuit breaker is proved.