The invention discloses an automatic expert comprehensive fault diagnosis system and a diagnosis method of a wind power unit, including: a data acquisition module, which collects relevant data of a main control unit and a vibration signal acquisition unit and transmits it to the fault diagnosis module; a fault diagnosis module, which is comprehensively used Neural network knowledge and expert system module knowledge, use forward reasoning and real-time parameter fluctuation values ββto compare with the data in the fault sample knowledge base, and generate fault information in real time; the fault diagnosis module will diagnose the fault information through the man-machine Interface module for output. The present invention uses the main control unit to read parameters such as wind turbine instantaneous power, rotational speed, propeller angle, cabin temperature, wind speed, oil temperature, yaw state, etc. to improve the accuracy of fault diagnosis, and utilizes the neural network expert system based on wavelet packet analysis Carry out automatic analysis, and give operation and maintenance suggestions through the expert diagnosis system.