Abstract: The chemical constitution and composition of the quaternary ammonium salt surfactant is briefly introduced, and the oil displacement mechanism of the surfactant is introduced in detail. According to the surface tension measurement, the critical micelle concentration of all cationic gemini surfactants ranges from 0.08% to 0.12%. The transient lowest interfacial tension between the gemini active water and the crude oil from Daqing Oilfield reaches 10–2mN/m when the concentration of the gemini active water is below 0.1%. The time of the oil/water interfacial tension reaching the equilibrium value will be increased because of the polymer, but the equilibrium value will not be influenced. After water flooding, the EOR will be increased by 10% or so when the multiple of pore volume of the surfactant solution is 0.15. Field test shows that the surfactant can be used to reduce pressure, stimulate injection and increase the production of oil wells.