As environmental problems have become more serious, a sustainable society is necessary. To realize the inverse manufacturing system the prime problem is how to improve the rate of reusing the product modules. Therefore analyzing the life-time of the disassembled modules is very important before reassembling process. In this paper, a cumulative damage model is proposed to discuss the quality of the product that is assembled by reuse modules. It is supposed that modules suffer damages due to shocks and fails when the cumulative damage level exceeds the failure level. Then maintenance cost will be analyzed in order to minimize the expected maintenance cost-rate by optimal maintenance time T and optimal number of damages N in this cumulative damage model. The probable safe life-time of module reuse will be explored. Finally numerical examples are given to confirm the validity of the proposed model.