Abstract: The viscosity of underground crude oil in Gucheng oilfield averages 650 mPa·s. In order to improve the development effect of water flooding in heavy oil reservoirs, the polymer/surfactant binary compound flooding tech nology was studied, and the formulation of binary compound system was optimized. Compared with water flooding, the viscosity of the binary composite system increased from 0.57 mPa·s to 81.1 mPa·s, the interfacial tension decreased from 19.2 mN/m to 2.70×10~(-2) mN/m, and the number of capillary tubes increased by 5 orders of magnitude. The emulsifying property of binary composite system can reduce the viscosity of crude oil, improve the viscosity of displacing fluid and further improve the fluidity ratio. The study shows that the binary compound flooding technology can improve the recovery rate by 15.99% and can be applied in the field of common heavy oil reservoirs with crude oil viscosity of 650 mPa·s.