Abstract: A novel combination flooding system is presented in this paper according to the characteristics of high crude viscosity and low water displacement efficiency in Menggulin sandstone reservoir. Slug design optimizationwas performed in laboratory based on evaluation of oil - water interfacial tension, compatibility and adsorbance. Experiments showed that mixed injection of combination slug not only can effectively lower oil - waterinterfacial tension and cut down adsorbance of surfactant on rock surface, but also can maintain mobility. Theoptimum combination slug design is :the concentration of surfactant being 0.5％, polymel 1400mg/L, slug size 0.1PVand using mixed injection method. Oil recovery factor isexpected to increasc 19％.