Abstract: Aiming at the problem of preventive maintenance in production system, the preventive maintenance strategy is put forward considering buffer inventory and service age regression. The influence of service age on failure rate is analyzed and the number of equipment failures calculated. A joint optimization decision-making model of equipment preventive maintenance plan and buffer inventory is established. This model takes preventive maintenance cycle T and buffer stock S as decision variables, and takes the total cost per unit time in the cycle CT(T, S) as the decision goal. The discrete iteration algorithm is used to solve the example simulation, to obtain the optimal inventory and preventive maintenance cycle, so as to minimize the total cost per unit time. The comparison of the examples shows that the strategy model can effectively save the production cost. Finally, through a sensitivity analysis, the influence of relevant parameters on the strategy model is obtained, which verifies the validity of the model and provides theoretical guidance for maintenance planning.