Due to the increasing population mobility and the growing world trade, the internationalization of law has become a matter of great significance. The confluence of Common Law and Civil Law is also accelerating. The second part of this thesis introduces the taxonomy in the legal systems of modern world as the exploring basis of this thesis. Part three illustrates the trend of the confluence of Common Law and Civil Law; Part four presents European Rules in American Law to verify the influence of European law to American Law. Part five explores the reception of American Law in Europe to demonstrate the reception of American Law in traditionally Civil law countries. Part six, in conclusion, contends that the confluence of Common and Civil Law presents some implications of legal methodology in Taiwan.