Smart water flooding is a new technology for oilfield development with low-cost，environmental protection and huge potential. Based on the research results of many scholars at home and abroad，the main mechanisms of the smart water flooding for enhanced oil recovery were analyzed and summarized as：alkali-like flooding，particulate migration，multicomponent ion exchange and reservoir wettability transition. EOR mechanism by the smart water flooding was verified by physical simulation experiments. The results show that the pH value of the produced water in the core flow experiment with the smart water flooding is significantly higher than that with the high-salinity water flooding；and the maximum pH value can reach 8.23，which indicates that the smart water flooding can exert the effect similar to the alkali flooding and improve the recovery factor. The smart water was used to displace the uncalcined and calcined cores at 650 ℃，and the ultimate recovery efficiency were 56.48% and 53.45%，respectively. The clay in the calcined cores no longer migrated，and the recovery efficiency was significantly lower than that of the uncalcined ones. It shows that the migration of the particulates in the process of smart water flooding can improve the recovery efficiency. By examining the concentration of each ion in the produced liquid during the smart water flooding，it is found that the Ca2+ concentration increases first and then decreases gradually，and the concentration of Mg2+ increases slightly and then decreases gradually and finally becomes stable. It shows that a small amount of Ca2+ ions was exchanged by Mg2+ and a large amount of Ca2+ on the clay surface was exchanged by H+ in the smart water during the water flooding. It shows that there are multicomponent ion exchange processes during the smart water flooding and the recovery efficiency is improved. After 70 hours，the smart water was applied around the oil droplet1.The contact angle between the oil droplet and the core gradually decreased from the initial value 124° to 67°. The wettability changes from lipophilic to hydrophilic. It indicates that the smart water flooding can change the wettability of the core surface and then enhance oil recovery.