The paper proposes that Confucianism has a high potentiality in inherent-ethics of rationalization, and such inherent-ethical rationalization is defined as harmonious rationality. The harmonious rationality is demonstrated from three aspects: the harmonious orientation of "benevolence" from the ethical aspect of Confucianism, "courtesy" from the aspect of system and " gentlemen " from the aspect of personality.The main content of the thesis is divided into three parts:1. It proposes the research frame of rationality. The research frame is obtained through analyzing the rationality concepts of Weber, Parsons and Habermas. It is composed of three aspects. The first is the theme of rationality and presupposition related to the theme, and the basis of rationality judgment decided by the theme and the presupposition. The theme of rationality is to establish the general criterion of experience (or experience knowledge and the presupposition of rationality is on the relationship between people and the world; and the basis of the rationality judgment is the orientation of the knowledge and the relationship between people and the world. The second is the research direction of rationality. The nature of the general criteria of experience (or experience knowledge) is different for different