Abstract: Japan’s “Phase III Marine Basic Plan” was based on the recommendations of the major think tanks. After longterm brewing, it was based on the plan of Japans marine thoughts after the Second World War and the postwar Japanese marine policy. It shows three distinct characteristics: the first is that changes in the surrounding marine security environment have prompted Japan to develop a basic marine plan that is different from the past, and the second is that the concept and direction of policy implementation have important innovations, making it more focused on the comprehensive protection of marine safety, the third is the change of specific countermeasures, more emphasis on the strengthening of the Ocean State Control (MDA) system and the strengthening of the strength and intensity of the protection of the southwestern islands and outlying islands. Strengthening comprehensive marine security policies and institutions will surely be the top priority of Japan’s “Defense Program Outline” in the future. The promulgation of this “plan” is an obvious negative asset for SinoJapanese security relations, which may bring a greater degree of obstruction to the continued easing of SinoJapanese relations.

Key words: Japan,Phase III Marine Basic Plan, comprehensive marine security Protection, security policy, internal and external impacts