The Asia Pacific regional security order is a mixture of bilateral military alliance and multilateral security dialogues that surrounding U.S-Japan military alliance. Asia Pacific is lack of the kind of regional collective defend system like NATO does in Europe. Though ARF provides a room of confidence building measure in Asia Pacific, it is not an effective multilateral security mechanism that can deter external aggression. To Taiwan, the external factors only U.S-Japan military alliance can provide effective rescue from PRC aggression. In this article, the author will try to analyze the Taiwan security under Asia Pacific regional security structure.