Abstract: The study of remaining oil is a main task of reservoir management during the mid-late period of oil field development, is an important means of controlling water cut and stabilizing oil production as well.When oil field enters the developmental phase of high water cut, the relation of water and oil will be more complex, the reservoir heterogeneity will be more severity, the distribution of remaining oil will be more disperse, the difficulty of stabilizing oil production and adjusting measure will be bigger.The paper, ba sed on the authors' achievements in projects research and general review of a quantity of literatures, expatiated present situation, primary technology and the distributing modes of remaining oil, and summarized the recent advance of remaining oil.