Abstract: In order to evaluate the enhanced oil recovery effect influencing factors of long-distance migration of weak alkali ASP flooding in class Ⅲ oil layer, this paper carried out the oil displacement experiment of weak alkali ASP system with using the independently designed and manufactured sand filling physical model of 30 m long pipe. The flooding dynamic, the changes of viscosity, interfacial tension and distribution of residual oil were studied. The results show that in the sand-filling physical model of class Ⅲ oil layer with an average permeability of 105.94×10^-3 μm², the weak alkali ASP flooding can be effectively injected into the layer, and increased recovery rate is 17.06% higher than water flooding recovery. The oil recovery effect for viscosity is the best in the near-well zone. The ultra-low interfacial tension of the weak alkali ASP system only maintains 8.9 m in the layer. The residual oil is slight in the near-well zone and a large amount of residual oil accumulates in the middle and deep areas of the layer. This is related to the change of viscosity and interfacial tension of weak alkali ASP system in the layer.