Abstract: In view of problems of high power consumption, voltage drop and big interference caused by downhole cable of surface substation using current-limiting reactance to limit short-circuit capacity, a solid state current limiter applied to coal mine power system was designed. The limiter is composed of solid circuit breaker and original current-limiting reactance. When power system works normally, the solid state current limiter bypasses the current-limiting reactance to avoid influences of the current-limiting reactance on power system. When power system has short-circuit fault, the solid state current limiter is broken from circuit, meanwhile the current-limiting reactance is inserted into the circuit to limit short-circuit current. Matlab simulation result validates feasibility of the solid state current limiter.