The production rate through water flooding in offshore oil field，Shengli oil province is decreasing year by year，it is urgent to convert water flooding to binary combination flooding to accelerate the development and improve producing efficiency. As an effective method to dramatically improve oil recovery and oil recovery rate，binary combination flooding technology has been widely used in onshore oil fields. However，due to the difference of reservoir conditions，offshore oil field cannot copy the reservoir development program from onshore oil fields. According to the technical requirements of binary combination flooding in offshore oil field，Shengli oil province，the key factors such as solubility，thermal stability and salt resistance of oil displacement agents are evaluated，and the selected polymer C10 and high-efficiency compound surfactant form the binary combination flooding system with excellent performance of compatibility and stability. The injection viscosity，injection rate and plug size are optimized based on physical simulation and numerical simulation. The results show that after the injection volume of 0.4 PV，the EOR of binary compound flooding system reaches 29.2%，which is 11.3% higher than that of single polymer flooding system with the same plug size. Under the condition of the optimal viscosity ratio of 0.5，the injection rate of 0.07 PV/a and the optimal injection plug size of 0.42 PV，numerical simulation predicted that the EOR of binary compound flooding is 11.6% higher than that of water flooding，which can obtain the maximum increase of the oil recovery rate and oil recovery in offshore oil field.