Aiming at the problems of poor flooding effect of water flooding，polymer flooding in high recovery degree and ultra-high water cut stage of high-temperature reservoir，anionic surfactants and cationic surfactants were used in combination，and an in-situ emulsification flooding system composed of 1500 mg/L polymer P5 + 0.3% surfactant S-2 was developed at the temperature of 95 ℃ ，and the phase characterization，reservoir water adaptability，natural core physical simulation oil displacement was carried out，and residual oil start-up mode displaced by microscopic lithography model were evaluated. Further， the heterogeneous core test was carried out to evaluate the displacement effect of the system at different size slug combination. The results showed that the prepared surfactant S-2 had good solubilization ability which can form microemulsion system in low mass fraction 0.1%—0.3% with crude oil in situ，the emulsion particle size were mainly distributed in range of 65—118 nm，forming an aggregate with vesicles，and it had ultra-low interfacial tension，good adsorption resistance and temperature resistance，and the oil washing efficiency was 78%. Considering the strong fluidity of the microemulsion，the optimized temperature resistant polymer had high mobility control capability under the water quality conditions of 0.2—0.4 mg/L oxygen content and 15—20 mg/L sulfur content，the viscosity retention rate achieved more than 100% after aging for 60 days at the temperature of 95 ℃. The experiment of natural core flooding showed that the phase characteristics of the produced liquid and core slice pores in in-situ emulsification flooding were obvious，the heavy components of crude oil were effectively displaced，and all types of remaining oil were well mobilized，which indicated that the system had the ability to form emulsification flooding in the whole process of displacement. The heterogeneous core test showed that the in-situ emulsion flooding system could increase the recovery rate by more than 25.2 percentage point through its variable concentration step injection combined with profile control slug injection. Considering the economic benefits and oil displacement effect，the combination injection mode of 0.1 PV profile control slug + 0.45 PV in-situ emulsification system + 0.05 PV profile control slug was selected. At present，the technology had entered the stage of pre-slug injection in the mine field，0.09 PV had been injected，the injection pressure increased by 5.0 MPa and the digital-analog predicted enhanced recovery rate was 8.06 percentage points.