SMEs play a signifi cant role in promoting economy by revitalizing the market, improving employment and promoting innovation. Countries, therefore, generally attach great importance to the development of SMEs and adopt legal measures and policies to support, guide and protect them. Meanwhile, international rules for SMEs start to grow in regional trade agreements (RTAs). Along with the emergence of the new type of RTAs, the issue of SMEs has become one of the horizontal issues and the number of related rules has increased significantly. SMEs issues begin to be prescribed in a separate chapter, reflecting international community’s rising attention to SMEs issues. Focusing on international rules for SMEs, this thesis takes a systematic review and analysis on international rules for SMEs in RTAs. By summarizing the international rules for SMEs in RTAs, this thesis concludes that the international rules for SMEs are still scattered, presenting characteristics such as encouragement-oriented and weak in binding force. Compared with the obstacles encountered by SMEs in international economic activities, the weakness of international rules for SMEs in RTAs constrains its role in supporting the development of SMEs, and there is still room for optimization and development of these rules. For China, international rules for SMEs are highly related to the principle of competitive neutrality reform and many development goals such as fair competition, inclusive development, scientific and technological innovation and economic transformation. Therefore, China should pay attention to the formation and development of international rules for SMEs in RTAs, realize the docking of domestic rules of law with international rules and lead the formation of international rules for SMEs.