In this paper, we deal with a simulation-based reliability and maintainability design problem of a warship and want to determine the optimal values of MTBF and MTTR of all units and ALDT of the warship. The system availability and life cycle cost are used as optimization criteria and estimated by simulation. A hybrid genetic algorithm with a heuristic method is proposed to find near-optimal solutions and numerical examples are also studied to investigate the effect of model parameters to the optimal solutions and compare with a general genetic algorithm.