The effects of HPAM, surfactant and solid particle on the stability of wastewater produced from surfactant/polymer flooding were investigated in terms of instable index, viscosity, interfacial tension and zeta potential. The results showed that HPAM had the greatest influence on the stability, followed by bentonite and surfactant (SDBS). Among, HPAM and SDBS had positive effect on stability, whereas bentonite had opposite effect. The increase of HPAM concentration contributed to the rise of viscosity which was the key factor of emulsion stability enhanced. The addition of SDBS could significantly reduce the interfacial tension, which made oil droplets more dispersed and ordered. Thus, the addition of SDBS prevented their coalescence and further enhanced the emulsion stability. Bentonite at a low concentration (less than 50 mg/L) as the cross-linking point, it could make the amide group and carboxylic acid group on the HPAM molecules with oil droplets and particles form OMA structures (oil-mineral aggregates), stabilizing emulsions synergistically. However, at a high concentration (more than 200 mg/L), the flocculation effect on the oil droplets was obvious, which caused the system to destabilize. Moreover, the same charge repulsion pushed more counterions into the sliding surface after the hydrolysis of HPAM, which resulted in the reduction of zeta potential. Therefore, the high viscosity and electrostatic repulsion were the main stabilization mechanism in complex multiphase emulsion. This study could provide a theoretical basis for the destabilization and oil-water separation of wastewater produced from surfactant/polymer flooding. Display omitted •The wastewater produced from surfactant/polymer flooding was proved to be a complex emulsion with high stability.•HPAM had the greatest influence on stability, followed by bentonite and SDBS.•HPAM contributed to the rise of the viscosity which was the key factor of emulsion stability enhanced.•SDBS could significantly reduce the interfacial tension, and thus prevent oil droplets coalescence.•Bentonite below 50 mg/L could be helpful to build complex network strucrures, while the system destabilized above 50 mg/L.