It is the film theory part to divide film research into three parts: film theory, film history and film criticism. Based on Aristotle's Four Causes Theory, film theory starts from four dimensions: material, method and skill, form and representation, purpose and value, and finds out the logical system of each genre theory and the uniqueness of the methods used. By comparing formalism with realism and combining modern French film theory, this paper fully traces and explains the viewpoints of important film theorists such as Mü nsterberg and Eisenstein, as well as the psychological and philosophical ideological basis behind them, and reveals them.