Hidden curriculum possesses the character and function of moral education. Different scholars' proposals of the methods and content of moral education are accordance with different bases of ethics. Functionalists propose that hidden curriculum should convey the ideas of group discipline: authority in the classroom is compulsory. This kind of hidden curriculum is established on the foundation of utilitarianism ethics, which emphasizes on disciplines and authority in group and management of order, but ignores individual will. Kolhberg's moral recognition development theory evolves the concepts that hidden curriculum can help grow students moral development and lead them to justice. This kind of hidden curriculum is based on the moral education of deontological ethics with the focus of ration of moral recognition, but overlooks the necessity of moral behaviors. Social critical theory advocates democracy and communicative actions, the development of students' critique of dominant ideology and distorted value, and emancipate the political-social relation in schooling. This kind of hidden curriculum belongs to the moral education of discourse ethics, which focus on participation of democracy and communication, but doesn't offer substantial referential criteria and possibly neglects the complex in the real society. By understanding different kinds of hidden curriculum, which might affect students' moral character, an educator can adopt a more open viewpoint and stance to accept and employ the significance of moral education in hidden curriculum.