Due to the extended lifespan of the platform, offshore reservoir development primarily relies on strong injection and recovery methods, resulting in an increased likelihood of entering a high water cut period, and the situation for stable production is critical. In this study, we propose a pore-throat scale composite system consisting of polymer microspheres and surfactants to enhance the recovery rate of Weizhou formation reservoir during its high water cut development phase in Weizhou 11-4N oilfield. The properties of polymer microspheres Q-2 and surfactant AP-1 as well as the compatibility and rheology of the composite system were evaluated. Core displacement experiments under different injection methods were carried out to optimize the injection method of polymer microsphere and surfactant. On this basis, the oil displacement efficiency evaluation experiment of the composite system was carried out through the parallel core model. The visual model was made to study the driving mechanism of the composite system. The experimental results demonstrate that: the median initial particle size of the microspheres is 3.755 μm, the expansion ratio is 2.15 after 30 days of aging, the residual resistance factor is 2.50, and the surfactants can reduce the interfacial tension between oil and water to 0.0185 mN/m. The compatibility between the two is good, and there is a shear dilution characteristic between the viscosity and shear rate of the composite system. The recovery rate of polymer microspheres and surfactants separated injection was 22.84%, which was 10.42% higher than that of mixed injection. After injecting the composite system, the recovery rate of parallel core model is increased by more than 18.79%. With the increase of the permeability grade difference of parallel core, the composite system improves the low permeability core more, and the recovery rate of low permeability core can be increased by more than 25.63%. The visualization experiment of flooding control and flooding shows that the composite system can effectively reduce the ineffective water circulation in high and medium permeability passages, start the crude oil in small pores, and improve the overall oil displacement efficiency. The research results lay a foundation for the field application of EOR technology in the late stage of high water cut development of Weizhou Formation reservoir.