The Eastern China Marginal Seas and the South China Sea are the important gateway for the Chinese National Security and Defense. The Subtropical North Pacific，where locates in west of the Second Island Chain, is not only the important region significantly concerned by many countries, but also the important passage of marching from costal to deep oceans for our nation. Centering on mechanisms of the interaction between the Subtropical Gyre in the North Pacific and China marginal seas via the Kuroshio, the National Basic Research Program of China, entitled" Variability of the Subtropical Gyre in the North Pacific and its impacts on dynamic environment of the China Marginal Seas" has launched a project on September 2007, This project will not only aim to extend and enrich theories of ocean dynamics, reveal variability mechanisms of costal and the adjacent deep oceans, and improve the prediction capability, but also provide assurance of ocean dynamic environment for the national defense, marine rights and interests protection, the safe and sustainable exploiture and utilization of marine resources.  The main research themes of this 973 project cover: (1) variability and adjustment mechanisms of Subtropical Gyre in the North Pacific; (2) processes and mechanisms of energy and water exchange between the Kuroshio and the China Marginal Seas; (3) coupling between variability of the Subtropical Gyre in the North Pacific and the atmospheric; and (4) predictability of dynamic environment variability of the marginal seas and the adjacent deep ocean. The key scientific issues to be resolved include: dynamics and mechanisms of subtropical North Pacific interior ocean circulation and its impacts on the Kuroshio, Variability mechanisms of the Kuroshio at its origin and impacts on the water exchange through Luzon Strait, and mechanisms of the Kuroshio variability and its impacts on dynamic environment of the China Marginal Seas.