Polymer- surfactant agent is characteristic of good viscosity increasing and emulsifying properties，it is necessary to analyse the cause that the production wells were of high emulsification ratio and prominent effect of emulsification in the field test of polymer- surfactan flooding after polymer flooding. The effects of different oil- water ratio，salinity，oil composition and concentration of polymer- surfactant agent on the properties of emulsion were studied，and the law of migration of emulsion produced by polymer-surfactant agent was analyzed through long core flooding experiments. The results showed that the polymer surfactant agent had emulsifying ability during polymer- surfactant flooding due to the surfactant interface activity and steric hindrance effect. When the concentration of polymer- surfactant agent reached up to the critical associating concentration，the emulsion stability further increased，and the emulsification phenomenon was more serious when the gum and asphaltene of the crude oil was higher. While，the salinity had little effect on the emulsification. Compared with polymer，the polymer- surfactant agent had a more uniform concentration distribution in the core，and the piston propelling effect was obvious. In the high permeability core，the polymer-surfactant agent could realize the emulsification at the initial stage of injection，producing time was of 0.2—0.8 PV. In the low permeability core，the emulsification became more obvious at the later stage of injection，and producing time was 0.5—0.8 PV. The emulsification type of the whole process was light and moderate oil-in-water emulsification，and the emulsification sealing position was about 58%—75% of the injection. Therefore，the fracturing time should be designed with the change of injection pressure during the emulsifying sealing，with a radius of at least 1/4 well spacing. The EOR was more than 2.5% through well-timed fracturing initiation.