After the cold war, the complex international situation has expanded the scope and range of subjects of international relations and security study. The framework of security study associated with international relations has been unable to meet the needs of researchers. In the past, culture and identity were considered the ”last resort” to explain international phenomenon; however, they have become critical subjects when studying international relations after the cold war. And discourses dominating international relations such as Neorealism and Neoliberalism have received more attention than ever. While the perspectives and reality of international security study underwent dramatic changes, Taiwan's security environment also witnessed a transformation and new security topics have kept appearing. Through the analyses of culture and identity within Constructivism, this paper attempts to review the development and the trend of international security study as well as probes into the impacts of culture and identity on Taiwan's national security. Constructivism advocates (most notably Alexander Wendt) underline that the structure of international political system, unlike Neorealism, has a social significance and emphasizes international system's function on its actors. Wendt argued that international structure not only influences actor's action but its ”identity”. And the ”identity”, based on ”shared idea”, also shapes the interest of actors. Therefore, Wendt proposed master-slave relations: only in a slave society, through the interactions with slaves can one act in accordance with his identity. The abovementioned ”shared idea” forms three cultures of anarchy: culture of Hobbes, culture of Locke and culture of Kant featuring enemies, rivals and friends. And they can be achieved through change of sovereignty action, actors' progressive collaboration and transforming ”egoistic identity” to ”collective identity”. In other words, Wendt believes anarchy is not invariable. It all depends on what kind of anarchy relations do two actors desire to form, or what kind of identity to establish. When considering Taiwan's security within international environment, the interaction between the US and PRC is inevitably the decisive factor and the priority in Taiwan's strategic deployment. Unconventional security threats have posed huge impact on Taiwan. From the constructive practical perspective, power is seen imbalanced in cross-strait relation. The reason the imbalance between Taiwan and PRC sustains is the exterior role played by the US and that Taiwan's stability is nearly decided by the growth and decline of strength of both sides. Hence, Taiwan's future security strategic mindset lies on the change of security environment under globalization so that the country can adjust national structure, exert asymmetrical mindset, expand self-strength and strike at enemy weakness. Meanwhile, Taiwan shall enhance the alternate application of its soft power and hard power, build up its influence and appeal, strengthen democratic image, advance international understanding of Taiwan, revise national strategy and policy and formulate correspondent actions positively, vigorously and comprehensively.