This study aimed to analyze the permanent magnets of PMSM demagnetized by first turn of the different phase belt short circuit fault. Firstly, parameters and coil structure of the designed machines were introduced. Secondly, the Finite Element model of PMSM was established with the ansoft software, which was used to simulate the permanent magnets of PMSM demagnetized by different fault types. Thirdly, current curves of short circuited coils and motor flux density vector of permanent-magnet motor were extracted under different faults. From two different aspects of the distribution of the winding, the relationship among the size of the demagnetization magnetic field, the size of the demagnetization area and the distribution of the demagnetization area were studied when first turn of the different phase belt short circuit faults occur. Our results proved that the demagnetization area and the distribution of the demagnetization area are related to the spatial position of the short circuit coils. Taken together, our findings not only can be used as the basis for judging short circuited coils and location of the demagnetization area, but also provide the technical reference for the design of permanent magnet synchronous motor.