Abstract: Demulsification of produced liquid by surfactant-polymer flooding from an oilfield was very difficulty, and the existing demulsification technology can’t satisfy the demand of oilfield. This paper analyzed the physicochemical properties and micro morphology of this produced liquid and compared the results with polymer flooding produced liquid by means of bottle test method and light-scatter method. A high efficiency demulsifier named DS had been developed based on the analysis. The experiments results show that a high oil-water separating velocity of the sample can be reached with 50mg/L DS added, and the oil in water phase can be decreased to 224.2mg/L in 1h. Moreover, the stability index of the sample is 14.95(compared with 6.31 of the existing demulsifier). It can be concluded that the DS can meet the demand for demulsification of the produced liquid for its higher efficiency compared with the existing demulsifier.