Abstract: In order to solve the problem that traditional expert system got knowledge hardly and connot solve new faults when diagnosing faults of asynchronous motor, the paper proposed a design scheme of expert system of fault diagnosis for asynchronous motor based on neural network and gave the system's structure and design of model of the neural network. The simulation result showed the system can combine advantages of expert system and neural network well and realizes expected target of fault diagnosis for asynchronous motor.