With the increasing economic exchanges between countries, international commercial arbitration, as an important way to resolve disputes, receives more and more attention. It is necessary to clarify the application of law in international commercial arbitration, which is mainly manifested in three aspects, namely, arbitration agreement, arbitration procedure issue and arbitration entity issue. Among them, the most important is the application of the law of the international commercial arbitration agreement, which is the premise and foundation for the study of the application of the international commercial arbitration law. Only by making clear this issue, can the substantive and procedural issues be further discussed. This paper will combine the arbitration legislation and applicable practices and related theories of various countries and relevant international organizations, compare the current situation in China, and fully analyze the application of law in international commercial arbitration agreements.