John Dewey’s thoughts on moral education were based on his ethical and psychological theory. As a moral philosopher, Dewey consciously stated for moral transformation. He welcomed the evolution from customary morality to reflective morality, treated morality as the process of the improvement of experience, and analyzed the moral standard of common good. As a psychologist, Dewey generally divided the process of conduct development into three stages, which are symbolized respectively by impulse, habit, and intelligence, and explained the spirally forming process of character within continuous experience. The moral trinity of the school can be regarded as the core of his moral education thoughts, which can be understood as a unity of social intelligence, social power and social interest from the perspective of the moral purpose of school education, and as a unity of the life of the school as a institution in itself,methods of learning and of doing work， and the school studies or curriculum from the perspective of the school moral education process. Dewey’s thoughts on moral education, represented by the moral trinity of the school, has great reference value for China in fulfilling its fundamental task of moral education and constructing a comprehensive school moral education system covering all members, the whole process and all subjects.