The characteristics of offshore field (large well spacing, low well density) mean that the oil recovery is comparatively low during the operation period of platforms, normally 20 years. The surfactant-polymer (SP) flooding is a potential EOR method for offshore field. The key challenges of SP flooding offshore are: ①high salinity and high divalent cation concentration of the injection water; ②limited space on the oil platforms; ③severe sanding problem in the pilot reservoirs and serious interlayer contradiction. Regarding to the sand groups of Ng4-5 in Chengbei 1 block, Chengdao field, the thorough study on the key techniques of offshore SP flooding has been performed, including formulation design, injection allocation, sand control, and plan optimization. Our findings are described as follows: firstly, a fast dissolving and salt resistant SP system is developed so as to meet the offshore field development requirement; secondly, a series of small injection facilities are set up for automatic process, thus, the high-efficient integrated injection has been achieved; thirdly, the layered sand control and water injection technique with low shearing is established, and lastly, the reservoir engineering plan of SP flooding is optimized. Our study is significant for improving oil production rate and recovery factor in offshore fields.