Abstract: In this paper, based on the background of motor eccentric fault diagnosis, the fault characteristic of the traditional motor current analysis method is weak, and it cannot deal with the non-stationary signal, hence order analysis technology is studied and is used to transform time domain non-stationary signal into angular domain stationary signal. In this paper, the eccentric fault model of motor is established. The influence of eccentric fault on motor current is analyzed. The fault characteristics in order spectrum are obtained or realize the eccentric fault diagnosis. Simulation and experimental results show that this method can detect the eccentric fault of motor during non-stationary operation process, and effectively overcome the "frequency ambiguity" phenomenon caused by traditional fast Fourier transform.