Abstract: After polymer flooding, the oil reservoir exhibits severe heterogeneity, and the remaining oil is generally highly dispersed, and the salt or alkali of ASP (alkali-surfactant-polymer) system have negative impacts. To address these problems, an alkali-free binary self-adapted system has been developed. Through experimental methods such as instrument detection and physical simulation, the nonionic surfactant suitable for high viscosity with PPG (pre-particle gel) particles was selected. The alkali-free binary self-adapted system was systematically evaluated, and a three-pipe parallel oil displacement experiment was conducted to verify the effect. The research results show that: when the concentration of A606 surfactant is between 0.05% and 0.4%, the alkali-free binary self-adapted system can achieve ultra-low interfacial tension of 10⁻³ mN/m level. Compared with the weak-alkali ASP self-adapted system, the alkali-free binary self-adapted system has better stability and emulsifying performance. After 90 days, the viscosity retention rate is 80.9% and ultra-low interfacial tension is maintained. The anti-adsorption performance is basically the same, and after 5 cycles of adsorption on oil sand, ultra-low interfacial tension is still maintained. After 6 adsorptions, the viscosity retention rate is 71%. Physical simulation experiments have shown that the alkali-free binary self-adapted system has better control and flooding effects than high concentration polymer flooding. Under optimal formulation conditions, the alkali-free binary self-adapted system applied after polymer flooding can increase oil recovery by 15.5% in the three tube parallel model.