In this paper, we propose a genetic algorithm (GA) to design a non-hierarchical and decentralized Multimedia-On-Demand (MOD) network architecture. To optimize the MOD network resource based on cost analysis including installation cost for servers, program storage cost, and transmission cost, the joint optimization of both server location and storage allocation was considered. In order to improve solution quality and computational efficiency in applying the proposed methods to the problem, genetic representation, evaluation function, genetic operators and procedure are devised. The results of extensive computational simulations showed that the proposed algorithm provided high quality solutions within a reasonable amount of computation time.