With the rapid development of new energy ships, electric propulsion ships in the maritime transportation in the status of higher and higher, but the new energy ship capacity is small, line impedance value is small, short-circuit fault current amplitude after the short-circuit fault is high, the rise speed is faster, the protection method of fast-acting high requirements. In this paper, for the new energy ship DC short-circuit, fault current rises rapidly and the peak value is very large, in-depth analysis of the new energy ship in the bidirectional Buck/Boost converter fault characteristics, and fully consider the impact of controllable devices in the converter on the fault characteristics, and puts forward a phased current limiting control method in the post-fault, for the capacitance response link to use the capacitance For the capacitive response, a capacitive fast removal device is used for current limiting; for the inductive response, phase shift control is used for current limiting. MATLAB/Simulink is used to build a simulation experiment platform, and the current limiting strategy proposed in this paper is simulated and verified, and the simulation results show that the proposed current limiting method can reduce the peak fault current by about 85%, and make the converter output fault current controllable after the fault, and realize constant current output.