After the Cold War, the security situation in East Asia seems to be relatively stable for the absence of wars and large-scale conflicts. However, the security cooperation in the region still lacks of political willingness, institutional arrangements and legal constrains. The widespread of security dilemma makes the threat of regional conflicts persist and there is little hope to solve the problem in short time. Under the trend of Regionalism, East Asian countries actively seek multilateral solution to build security community in order to ease security dilemma. However, The American mode bilateral-preferred security arrangement still dominates the regional security cooperation structure. The historical issues, culture and interests disputes also increase the difficulty to build mutual trust between states within the region. Considering about the internal and external security environment, there are possibilities for Southeast Asia to achieve multilateral solution in easing the regional system-induced security dilemma. As for Northeast Asia, the security dilemma is more like state-induced security dilemma. Under the fragile Locke Culture, They have little willingness to build security cooperation mechanism and thus promote mutual trust to ease security dilemma. For the whole East Asia, the possibility to use multilateral solution and build security community is also very small. The study of multilateral security mechanisms in Southeast Asia and Northeast Asia II shows that the existing mechanisms are not effective enough to solve the security crisis in the region. Although financial crisis, terrorism and other transnational threat provide more motivation for states to cooperate with each other, the driving force is still not enough to establish an effective multilateral security structure right now. Therefore, the possible path for East Asia to achieve multilateral solution is to improve the existing security mechanism to promote political transparency and mutual trust. Every state should recognize that every conflict is threat to regional peace and stability, and they should never pursue national interests through force nor war.