Whether and how Chinese courts can apply treaties in foreign-related trials is both a theoretical issue and a practical one. It is related to the basic function of the treaty and the status of the treaty in domestic law, as well as the status and power of the judiciary in a country’s external relations. Both the existing domestic law and the customary international law of“Pacta Sunt Servanda”imply that treaties are effective in domestic law and should prevail over domestic law. Although recognizing the validity of treaties in domestic law does not mean that courts should apply treaties in adjudications. While there is no consistent practice in this regard in judicial practice related to foreign affairs, the Supreme Court has recently raised the issue of proper application of treaties, which indirectly acknowledges that treaties are important legal basis for international adjudication. With the gradual unfolding of the Belt and Road Initiatives, especially in the context of the establishment of international commercial courts, Chinese courts will inevitably face the issue of applicability of treaties in foreign-related trials. It is therefore submitted: there is a need to distinguish between directly applicable treaties and treaties that serve as a basis for interpretation; the treaties that directly set rights for individuals can be directly applied; the provisions of treaties must be absorbed through judicial interpretation before being applied; at the same time, the research on judicial application of treaties shall be strengthened; and the principles of necessity, legitimacy, interpretativeness and consistency should be emphasized in the application of treaties to foreign-related trials.