Abstract: Wind power systems are often installed where is remote，inaccessible or the climate is not suitable for human to stay for long
time． So the traditional scheduled maintenance and breakdown maintenance can not meet the demands． It is very essential to ensure re-
liable and stable operation，and to reduce the cost of maintenance，condition monitoring and fault diagnosis of wind power system． The
existing fault diagnosis methods for the main failure components of wind power system，including gear boxes，generator，power electronic
devices，blade and so on，were introduced and classified． This work will provide an effective reference to the improvemet of the reliability of wind power system，reduction of cost and promoting the engineering process．