The Type I and II reservoir resources suitable for chemical flooding in Shengli Oilfield have been basically produced，and the resource replacement is difficult by chemical flooding. An injection-production coupling technology is designed to prolong the economic validity period of polymer flooding projects at later stage. Based on the physical simulation experiment，a visualized simulated displacement apparatus is used to study the swept volume and the residual oil distribution characteristics under conventional injection-production and injection-production coupling technology at the later stage of polymer flooding. The results show that compared with conventional injection-production methods，injection-production coupling approach can change the direction of conventional streamline，enlarge the swept volume and produce the remaining oil in low permeability area to achieve the purpose of enhancing oil recovery. Taking Ng3-4 unit in No.8 Block of Gudong Oilfield during polymer flooding at the later stage as an example，a reservoir numerical model for the Ng32 Submember is established. The optimization of injection-production coupling structure and implementation cycle is performed by numerical simulation. The results show that the coupling technology for chemical flooding can effectively transform the existing streamlines，expand the swept area of the diversion streamline，reduce the usage of chemical agents and further improve oil recovery in the reservoir under extra-high water cut stage. The optimized coupling structure of injection-production is the symmetrical structure with the ratio of production time between one round to two rounds being 1∶1. The production time of each round is three months. Then ten well groups are selected to carry out field test. After field implementation，the water-cut returning trend is effectively controlled，the dry powder of polymer is reduced by 10.8 tons per month and the incremental oil production per ton of polymer is increased by 7.6 t/t. The enhanced oil recovery is predicted to further increase by 1.7%.