In order to prvoide the new clue for the later tapping oil potential of maturing oilfiled, especially for thestratagem adjustment of high water-cut inefficient exploitation reservoir, and prolongate the realm and orientation of tapping oil potential, the waterflooding characteristics and the law of remaining oil distribution were studied.By taking A fault block of ShengLi oil field with high permeation,greatly thickness and high water-cut oil reservior as the example, the development effectiveness, the flooding characteristic and the remaining oil distribution rule have been conducted the synthetic study. The result indicated that the recovery of this fault block is only 11.9%, but the forecasting recovery is above 23%, more than 50% recoverable resources has not picked; The remaining oil distributes in the plane in the sub-area major part region, on longitudinal mainly concentrates in 7 main force subzones, particularly ES1-32, ES2-13, ES2-22, the ES2-23 subzone, the surplus recoverable resources is more than 3?04t , they are the main potential object in the future. In addition, in the system research and the summary foundation, two kind of main remaining oil distributed patterns for the A fault block are proposed.