In the sixth issue of Jurist in 2021, Guo Dong wrote that the question of "what makes the social science research of laws possible" is full of multiple competing propositions. Most of the previous arguments in this regard basically did not start from the fact that that law is a normative science in terms of disciplinary attribute, so it is incomplete. Unlike legal doctrine, which uses legal norms to identify, contain and evaluate facts, the social science research on laws is committed to describing, explaining and predicting facts. The empirical facts concerned by the social science of law can be divided into facts about laws and laws as facts. These two kinds of fact studies provide knowledge for legal doctrine in the sense of knowledge achievements and research methods, and fill the methodological gaps of legal doctrine.