This article discussed such general theory as the logical relations between the source of law and the theory of knowledge. The author holds that modern code-law is based on the rationalistic theory of knowability. On the contrary, the theory of scepticistic agnosticism has played great role in the shaping of English precedent-law tradition. Henceforth, the appearance of the eclecticism cognitive theory led to the “mixed-law” in civil law system and common law system. According to the theory of knowledge of dialectical materialism, the author suggested that contemporary China should choose a “mixed-law” model of legal source, which means the fusion of code-law and precedent-law. And the Chinese form of legal source should take code-law as the principal and precedent-law as the subsidary.