Twenty years ago, Peter M. Haas, an American political scientist, introduced the concept of "epistemic communities", assuming that groups of specialists can influence the perspective on interests of policy makers. The approaches of epistemic communities are noticed by both academic and political circles mainly due to their ability of increasing influence in promoting international cooperation (namely non-traditional security issues) if some conditions are highly satisfied. Based on those approaches, the article proposed the method of studying epistemic communities as a target of transnational research in cooperation to resolve disputes in the East Sea. Through the knowledge dissemination of epistemic communities, short-term practical solutions for the East Sea can be transformed into long-term highly institutionalized undertakings. Especially when the study on international security mainly focuses on state-centered approach, the methods of epistemic communities give us new views to learn about the policy planning process.