From the perspective of institutional economics, this paper analyzed the effects of regional economic integration on the process of multilateral free trade. Starting from the practical situation in the Asian-Pacific region, this paper, by comparing the European Union (EU) and the North American Free Trade Agreement (NAFTA), systematically studies the theory of international economic integration and brings forth some important innovative ideas on the development of Asia-Pacific economic cooperation (APEC). According to the results, as the original intention of the Asia-Pacific Economic Corporation (APEC), the promotion of trade liberalization benefits both APEC members and non-members, which is the goal of open regionalism and provides great prospects for the future development from regional integration to global multilateral trade liberalization.