In this study, simulated the reservoir conditions of Suizhong 36-1 offshore oilfield, the optimization experiments of injection timing and injection pattern of the binary composite flooding after polymer flooding were developed. After polymer flooding, the launching of binary composite system was studied at different injection timing, including direct injection, water content ratio of the lowest point, 70% and 95%. The results showed that the ultimate recovery rate was 75.36%, 73.32%, 71.22% and 68.61%. The oil recovery of binary composite flooding in directly conversion after polymer flooding was the highest (42.61%). At the same water flooding conditions, the effect of injection mode of binary composite system on oil displacement efficiency was compared. The result showed that the oil displacement efficiency of 0.3 PV binary composite system was better than that of 0.05 PV polymer+0.2 PV binary composite system+0.05 PV polymer and that of 0.1 PV polymer+0.2 PV binary composite system. But the effect of injection mode on the ultimate recovery rate was not big. Using polymer as protection slug was more advantageous to control the cost of industrialization. And the flooding effect of before and after protection polymer slug was better than that of single front slug if polymer dosage of the slug was same. Under the same economic condition, the oil recovery ratio of polymer+0.3 PV binary composite flooding increased 19.05%, which was higher than that of the equivalent 0.7 PV polymer flooding by 1.61%, maximizing the overall effectiveness of oilfield development.