Legal interpretation cannot be separated from appropriate understanding of the conceptions of legal institutions, and legal norms are embedded and interconnected in legal institutions. Therefore, the clarification, understanding and interpretation of conceptions of legal institutions are prerequisite for interpretation and application of legal norms. Through the examination of related cases and legal rules, the article points out that legal ethics is concerned with conflict of interests and collisions of legal norms. Personal morality, therefore, is not an appropriate foundation of legal ethics. As the conclusion, the article argues that the basic knowledge of ethical theories and moral reasoning should be emphasized in the research and teaching of legal ethics. The courses of fundamental legal studies should be strengthened in legal education as well.