Abstract: Axial Flux permanent magnet synchronous motors operated in humid, high temperature and vibration environments for long periods of time are prone to turn-to-turn short circuits and permanent magnet demagnetization coupling faults. This paper is a feature analysis of the signals generated by coupling faults. First, we established a three-dimensional finite element model of the motor starting from the working principle of the motor, and determined that the proposed motor model is compatible with the actual motor by comparing the experimental data and simulation results. Then, we implemented simulations of turn-to-turn short-circuit faults, permanent magnet demagnetization faults and coupling faults in combination with simplorer. Finally, we compared the characteristic quantities such as electromagnetic torque, induced potential and fault phase current of the motor model under different fault states, and analyzed the variation of the harmonic content of each order of the characteristic quantities. The results identify the characteristic quantities that effectively distinguish between single turn-to-turn short-circuit fault, single permanent magnet demagnetization fault and coupling fault as the fractional harmonic content of induced potential and the current pulsation with polar logarithmic period of the fault phase current respectively, which provide some reference basis for the fault characterization of this type of motor.