This article examines the effect of oil viscosity, permeability, and residual oil saturation on the performance of alkaline flooding to enhance heavy oil recovery. The results show that the in situ generated water-in-oil emulsion during alkaline flooding can effectively improve sweep efficiency and, consequently, improve heavy oil recovery. The tertiary oil recovery can reach over 20% of the initial oil in place using 1.0% NaOH. The incremental oil recovery of alkaline flooding increases with the residual oil saturation. However, the tertiary oil recovery gradually increases with decreasing the permeability. But the effectiveness of alkaline flooding does not decrease with the increasing oil viscosity.