Due to the rapid development of social productivity, the complex electromechanical system has become one of the important components of industrial automation domain. The complex electromechanical system is becoming more advanced in terms of intellection and automation. Consequently the demand in maintenance ability has been raised to a higher level. Whereas the major domestic complex electromechanical systems sustain a periodic maintenance and posterior maintenance mode currently, which indicates the development of maintenance technique is clearly fall behind the development of equipment. This paper is based on fault prediction, prognostic and health management (PHM) technique and combined with the analyses of common fault patterns in complex electromechanical system, studied the health management system of complex electromechanical system in terms of hierarchy, functional composition and technical approach. It provides positive discoveries for on-conditional maintenance mode applying to complex electromechanical systems.