The East marginal seas of China is the most important economical sea area supporting the prosperity of the Chinese nation. Its strategic status and economy contribution are extremely important to the development of our country. The in-depth research and understanding of the ocean environment and biological materials, help achieve fundamental benefit of our country and the grand goal of speeding the establishment of a Harmonious society. Therefore, the emergent mission we have to face now is to carry out in-depth research on this sea area. In order to lay groundwork for revealing the tendency of ocean environment evolvement and providing scientific support for the security of national defense and fishery production, a National Key Basic Research Science Foundation (973 project) “Marine Physical Variations in Eastern Marginal Seas of China and their Environmental Impacts” (2005CB422300) has been designed to make an in-depth study of the evolvement of physical environment and the environment impacts on the east seas of China which is a complex dynamics system in possession of changeable stratification structure and coupled multi-movement form. The research purpose, science significance, key scientific problems and expected goals are briefly introduced in this article.