Abstract: This research analyzes the historical changes of the principle of proximate cause in marine insurance law and related cases, and compares it with the principle of causality in tort law. As far as the criteria are concerned, the principle of proximate cause and the principle of causality only recognize the uniqueness of proximate cause, and follow the "theory of effectiveness" and "principle of common sense". The difference between them is that the former only focuses on whether the causation belongs to the risk covered while the latter focuses on whether the insured is at fault yet. In terms of "multiple causes and one effect", both laws recognize the diversity of causes, tort law follows the principle of "joint of causes", while marine insurance law follows the principle of "composite standard" to judge causes. The differences are: in tort law, the actor bears the liability of compensation according to the "proportion of fault"; in marine insurance law, the insurer still bears the liability of compensation in accordance with "all or nothing". With the development of Japanese judicial practice and the introduction of Norwegian marine insurance clauses, the convergence of the two is reflected in: in the determination of the consequences of damage and compensation, the principle of tort law is used for reference, and in the case of damage caused by mixed causes, the principle of loss distribution is followed. The revision of Chinese Maritime Law should be based on respecting the existing judicial practice and referring to the provisions of tort law: for the judgment of causality, only consider whether the causation belongs to the risk covered; for the determination of compensation, while recognizing "multiple causes and one effect", consider to adopt the principle of "proportion of fault".