Professional Ethics stresses the importance of following the ethical norms of each profession. General ethical standards seem still to enjoy general acceptance. The only gap is between knowledge and practice. To strengthen professional ethics, the awareness of our inner ethical values is necessary. In his methods for studying Zhu Xi (1130-1200) not only spells out the methods for studying, but he instruct us about the difference between human desires and general norms (heavenly norms) and ways to transform the one into the other. This paper uses Zhu Xi's methods of studying from traditional Confucian thought to expound the importance of a serious attitude towards our profession. The paper consists of three parts: In the first part Zhu Xi's method of studying is discussed, in the second part the meaning of professional ethics is explained, in the third part professional ethics is discussed from a perspective based on Zhu Xi's method of studying.