In order to reduce the risk of destructive physical tests such as short circuits, a corresponding short-circuit fault protection and power supply redundancy conversion mechanism is designed in the light of a certain of small aircraft power supply architecture. Based on AMESim, a complete power system and backend load model are established, and protection logic is injected to simulate actual faults and predict phenomena. The established power supply and electromechanical management model can simulate faults such as generator main feeder short circuit and busbar short circuit to a certain extent, and automatically execute protection logic. The results show that the interruption conversion time of the collector voltage in the short-circuit protection is less than 50 ms, and the back-end actuator and electric pump can work normally under condition of non-emergency short-circuit faults. The designed protection logic is basically appropriate. The maximum impulse current of system short circuit is 2 898.5 A, and the maximum reverse current of motor is 38.4 A, providing reference for subsequent device selection and physical testing.