Abstract: Taking a 2.2 kW 380 V IPMSM (Interior Permanent Magnet Synchronous Motor) as the research object, the two-dimensional finite element model is established by using finite element analysis software and the external circuit is built using the Maxwell circuit.The short circuit faults of the motor during the running process are realized using the voltage control switch.Extracting the minimum magnetic flux density of the permanent magnet in the process of short circuit faults to generate the magnetic cloud image with the help of macro file, it is the basis for judging the demagnetization of permanent magnets.If the minimum flux density under different short circuit faults is lower than the knee-point magnetic density of the demagnetization curve at the corresponding temperature, the permanent magnet in the region is demagnetized.The analysis results provide a theoretical basis for analyzing the demagnetization fault of permanent magnet motor.