According to the problems of tertiary chemical flooding in Dagang oilfield，such as high cost，poor environmental protection and unsatisfactory effect of improving oil recovery， surfactant flooding， polymer-surfactant binary flooding， polymer-surfactant-alkali ternary flooding efficiency systems were prepared by combining the environmentally degradable circular microbial surfactant synergist，petroleum sulfonate and polymer. The surface tension，oil-water interface tension，salt resistance， biodegradability， temperature resistance， anti-adsorption resistance and oil displacement properties of the microbial oil displacement system were evaluated. Taking crude oil and the extracted water from the second area of Dagang oilfield as the medium，the adaptability between efficiency system and reservoir was evaluated，and then the oil flooding test of 1 well with binary efficiency system was carried out in 5-XX well of Yangerzhuangyang. The results showed that compared to a single petroleum sulfonate system，the performance of the microbial surfactant synergistic oil displacement system was significantly improved. The surface tension could be reduced to 18 mN/m，the oil-water interface tension could still reach the order of 10^-3 mN/m after 8 times of dilution，the sodium salt resisting concentration was up to 75 g/L，the magnesium salt resisting concentration was up to 2000 mg/L，the temperature resistance was up to 90 ℃，the biodegradation rate of 45 d was 93.9% ，and then the anti-adsorption was up to four level. Microbial surfactant synergist had good compatibility with polymer and weak base. It would not affect the oil-water interface tension and anti-adsorption performance of binary and ternary oil flooding systems. Furthermore， the viscosity stability was improved. The viscosity retention rate of binary and ternary flooding systems after closed standing at 58 ℃ for 7 d was about 72% and 68%，respectively. Microbial surfactant synergist could improve the displacement efficiency of surfactant flooding，binary flooding and ternary flooding，with more than 17% the recovery increase. Under six different reservoir conditions in Dagang oilfield，the microbial surfactant synergist had good adaptation. The oil-water interface tension of oil displacement system could reach the order of 10^-3—10^-4 mN/m. When the microbial surfactant synergist was produced in a pilot scale and used in the field oil flooding test，the moisture content decreased by 31.5% on average，the cumulative oil increase in 8 months was 491.34 t，showing good water control and oil increasing effect.