Polymer/surfactant flooding produced liquid is difficult to treat compared with water flooding due to large quantities of residual chemicals which lead to serious emulsification. Dewatering rate of O/W emulsions by bottle test, particle size distribution measurement and multiple light scattering measurements were employed to study the stability of the O/W emulsions stabilized by both polymer and surfactant. O/W emulsions stabilized by polymer and surfactant get more stable when polymer/surfactant concentration increased. Polymer contributes more to the stability of O/W emulsions compared with surfactant. Polymer concentration is the key factor to stabilize O/W emulsion because polymer can form rigid cross-link network at oil-water interface to enhance the stability of the emulsions while polymer can enhance the viscosity of water and thus decrease the collision probability of oil droplets.