With the proportion of wind power and capacity of the unit are increasing in China,If the unit is in the event of accident, which not only affect the safety of wind farm itself, but also will have a significant impact to the stability of the operation of power grids. Fault analysis and intelligent diagnosis technology is one of the primary means in reducing the failure rate and the cost of operation and maintenance of large wind turbines. The main components' faults of wind turbine generator set are analyzed in detail. On the basis of further research about condition monitoring and diagnosis technologies of wind turbine, the new method of intelligent diagnosis based on wavelet packets and BP neutral network is proposed, which is responsible for the development of the condition monitoring and malfunction of the condition monitoring and malfunction diagnosis system of wind turbine. Then the validity of the whole system is verified by the system's successful application in a large scale wind turbine generator field. © 2016, Xi'an High Voltage Apparatus Research Institute Co., Ltd. All right reserved.