[Purposes] The maintenance plan of the stay cables should be proposed by weighing decisions from various perspectives,in order to make the best use of limited resources to obtain the optimal maintenance effect and ensure a safe in-service operation.[Methods] Based on the resistance degradation model of stay cables, the time-varying reliability during the service period was analyzed.The reliability of the target was taken as the basic constraint.The cumulative failure probability and maintenance economic cost of the stay cable were expected to be minimized during the service period. Based on the preventive maintenance and necessary maintenance,a combined model of maintenance strategies for stay cables was established.The model was solved and analyzed by the non-dominant ranking genetic algorithm (non-dominated sorting genetic algorithm II, NSGA-II).By approximating the ideal solution decision,the optimal maintenance scheme was obtained from the selection of a large number of non-dominant solutions. [Findings] Compared with the necessary maintenance alone,the combination maintenance strategy formed by appropriate preventive maintenance activities significantly reduces the reliability degradation rate of stay cable components,saving 7.4% maintenance cost.[Conclusions] The results show that the time-varying reliability of the stay cable can be calculated and analyzed with the established cable resistance degradation model.This provides a performance index basis for the optimization of the stay cable maintenance strategy. The comprehensive balance between maintenance effect and economic cost is realized through the combined maintenance strategy of the stay cable. The reasonable time arrangement for the implementation of preventive maintenance activities can reduce the times of the necessary maintenance, save a large amount of maintenance costs while meeting the performance requirements.