Abstract: For simulating the long distance flooding process of real reservoir more accurately, the paper established a length of 30 meters flooding physical model. The model has multiple measurement points and sampling points along the way to monitor the changes of pressure and the properties of displacing agent in course of flooding. The results showed that: from the beginning of ASP flooding, when injected 0.5PV, the effect of ASP began to appear; when injected 0.9PV, the ASP showed the best results, when injected 1.4PV, the effect of ASP began to disappear; the interfacial tension could achieve ultra low status only in a short time and in the beginning of 10% distance, the contribution of improvement recovery degree is only 7.7%, it means that the contribution of ultra-low interfacial tension is limited. When the oil displacement efficiency is higher, the viscosity retention rate in the entire length tube is relatively higher, and residual oil saturation is also higher when the viscosity retention rate is the highest, which has made the major contribution to the oil displacement efficiency. Thus the ultra-low interfacial tension is not an indispensable factor to improve oil recovery, but the viscosity and its retention rate are crucial and should be taken seriously enough.