Establishing a harmonious socialist society is a significant strategy in our country recently. To realize the goal, constructing psychological harmony among social members is the basic requirement and important foundation. By elaborating the concept of entropy ,the principle of entropy and the theory of consumption structure systematically, this paper analyzes the necessary condition required by psychological system as a kind of consumption structure, Through analyzing the psychological system based on entropy, this paper discusses the approaches of constructing psychological harmony and analyzes an actual cases of morita therapy , offering a new theoretical angle for study of psychological harmony.