As an important curve to understand the law of water flooding, the relationship between water cut and displacement multiples plays an important guiding role in understanding the rules of oilfield flooding, tapping the remaining oil and the law of water cut. However, during the experiment, due to the small size of core and high viscosity of crude oil and water, the accurate experimental data can not be obtained during the dry recovery period, the low water cut period or the middle water cut period, and the abnormal curve appears. The paper creatively establishes mathematical relation between water cut and displacement multiple, and corrects three kinds of abnormal curves of water cut and displacement multiple obtained from water flooding experiments in some heavy oilfields of Bohai Sea. According to the corrected curve, the water flooded map of M5⁃2 oilfield is drown up,which guides the remaining oil tapping the potential of the field.