Abstract: The remaining oil distribution in cyclothem is playing more and more important role in the later period of oilfield development,so it is very important to study the remaining oil distribution in cyclothem for the later development adjustment of the high water-cut reservoirs using the fine numerical reservoir simulation.Conceptual models have been built on the basis of geological condition of 8th sand set of Sheng II Block in Shengtuo Oilfield to analyze the distribution rule of remaining oil in the same cyclothem.The results show that,when water flooding is calculated till the high water-cut period,vertically,remaining oil saturation of upper layers is high and that of lower layers is low and close to irreducible oil saturation in the same cyclothem.Furthermore,the smaller the layer thickness,the bigger the density difference between oil and water,and the smaller the oil viscosity,the more obvious this trend will be.But the location of perforation in injection wells has little effect on the remaining oil distribution.So the upper layers in cyclothem should be the target for later development adjustment in high water-cut period of Shengtuo Oilfield.