Aiming at the application of prognostic and health management （PHM） technology in civil aircraft maintenance engineering， this paper discusses the design of predictive maintenance mode based on PHM， and puts forward the analysis process of initial maintenance task considering PHM and the implementation method of predictive maintenance mode based on PHM. Taking B737NG air conditioning system as an example， the validation research is carried out， the PHM model of air conditioning system based on data drive is established， the PHM maintenance mode of air conditioning system is designed， and the maintenance cost under planned maintenance mode and predicted maintenance mode is compared and analyzed based on historical operation data. The results show that the maintenance mode based on PHM can both cancel some regular inspections， and reduce unplanned maintenance events through early monitoring， so as to reduce the life-cycle maintenance cost of civil aircraft system. Cost benefit analysis shows that compared with traditional planned maintenance， PHM maintenance can reduce the cost by more than 40%. Further popularization and application to other systems of the whole machine will bring greater economic and safety benefits.