<p>The supervision of the maintenance of industrial facilities, especially the expenses related to the application of preventive strategies, is of increasing importance due to the growing role of this service in the production chains. This article presents a model of periodic preventive maintenance policy (fixed period/ variable period) based on the concept of reducing the age of the components of a system. Accordingly, three maintenance activities can be applied to system components, simple preventive maintenance action,preventive revisions and preventive replacement. The combination of optimum activities requires identifying the preventive maintenance actions and intervals necessary for them on each stage using genetic algorithms. The objective is to determine the activities and the optimal interval at each preventive maintenance step, extending the lifetime of a system subjected to degradation, considering the maintenance cost for the three types of activities and the minimum repair costs for each preventive maintenance step. In this study, we applied the optimization technique by the genetic algorithm with the aim of minimizing the preventive maintenance policies cost and to optimize the activities of a multi-component mechanical production system. The optimal activities and intervention interval that maximize the system lifetime per unit cost at each preventive maintenance stage can be determined using genetic algorithm. The results indicate that preventive maintenance with variable intervals extends system lifetime more effectively than constant intervals.</p>