The purpose of this article is to investigate the happiness principles and the educational aims of Confucius and Thomas Aquinas. To discuss this study logically, three research questions are addressed. First, what are the principles of happiness of Confucius and Thomas Aquinas? Second, what are the aims of education of Confucius and Thomas Aquinas? Third, what are significant similarities and differences between Confucius and Thomas Aquinas? In order to defend the research questions, a descriptive content analysis method will be used with a cross cultural approach. As for the limitations of this study, the principles of happiness are mainly discussed from the aspects of earthly life and of afterlife. The aims of education are limited to individual and social purposes. This paper is mainly focused on "The Analects" of Confucius, and on "The Summa Theologica" of St. Thomas Aquinas. The significance of the study is to provide the basic theories and valuable resources of happiness education and religion education for educational theorists and practitioners in the world in terms of the mutual understanding of the Eastern and the Western cultures. The findings of this study are: Confucius' view on happiness principles is morally anthropological and pragmatic, whereas Aquinas' view is piously theological and metaphysical; and in the aspect of educational aims, Confucius has a morally human view, while Aquinas has a religiously theological view.