It is of great significance to clarify the microscopic remaining oil occurrence characteristics and production mechanism of typical oilfields in Bohai Sea in the high water cut stage to guide the enhanced oil recovery of oilfields in the later stage of water flooding. Based on the spatial occurrence state and distribution dynamic change of microscopic remaining oil in complex pore-throat network structure, the evolution law of microscopic remaining oil in water flooding process is analyzed. Based on the micro-remaining oil classification method combining genetic mechanism and spatial occurrence form, the micro-remaining oil in high water cut stage was quantitatively characterized, and the classification standard of micro-remaining oil occurrence form was formed. By analyzing the micro-remaining oil content of five forms of different sedimentary microfacies, the micro-remaining oil content in pores of different sizes is determined, and the occurrence characteristics and utilization mechanism of micro-remaining oil in high water cut stage of typical oilfields in Bohai Sea are clarified. Through the water flooding experiment of rock slices under different hydrodynamic conditions, the mechanism of micro-remaining oil in high water cut stage is clarified. Studies have shown that after the high water cut period, increasing the displacement speed can significantly increase the dispersion coefficient, and the proportion of cluster residual oil is significantly reduced, and gradually transformed into discontinuous residual oil such as throat, drip, and corner adsorption. After changing the displacement direction, the remaining oil content of the cluster is reduced to 6.11%, and the remaining oil of the discontinuous phase such as throat, drip, corner adsorption and pore surface film accounts for 6.32%. By increasing the pore sweep rate and using the cluster remaining oil in the non-dominant channel, the cluster remaining oil is divided and sheared into dispersed remaining oil to be produced. The research innovatively clarifies the occurrence state and utilization mechanism of remaining oil in the high water cut stage of typical oilfields in Bohai Sea, which can provide support for improving recovery in the later stage of similar oilfield development.