Abstract: Alkali/surfactant/polymer flooding has been drawn great attention by petroleum workers because of its good effects on increasing oil recovery. But it was not used extensively for the high price of flooding a-gents and its great loss in reservoir. In order to understand changing characteristics of viscosity and interfa-cial tension of flooding agent in ASP flooding, directed by similarity theory, using physical simulation and instrumental detection, researches on changes and influential factors of viscosity and interfacial tension of flooding agent in ASP flooding were carried on. The results show that viscosity increases and interfacial tension decreases as the increase of the injection rate or PV. If the PV is the same, the nearer from the in-jection well, the higher the viscosity is and the lower the interfacial tension is. Because of retention and di-lution of ASP system, viscosity decreases and interfacial tension increases during the migration of ASP sys-tem in reservoir.