The hazard degree of TH65140 heavy-duty CNC machine tool each subsystem were analyzed to develop a cost-effective preventive maintenance strategy.Reliability modeling of heavy-duty CNC machine tools was carried out through the Weibull distribution,under the reliability constraints,the periodic preventive maintenance model of a machine tool subsystem was established with the goal of minimizing the maintenance cost and maximizing the availability,and the optimal number of maintenance times and maintenance intervals were obtained by solving the model,and the preventive maintenance strategy for heavy-duty CNC machine tools was formulated.