To improve the efficiency of maintaining and servicing Aero REPM-BLDCM, detecting the fault in time is of great importance. Thus, an efficient method of failure diagnosis and mistake detection, by using the inherent characteristic of running BLDCM, through an analysis of bus-current ripple and in combination with Hall position signal, is put forward. Combing with Hall-signal, the DC-link current ripple wave can help filter out the broken switch tube. The correctness of the result based on theoretical analysis is tested and verified by simulation and experiment, which offers a scientific reference for the further researches in electronic protector and fault diagnosis device of REPM-BLDCM.