Abstract: Optimizing chemical slugs is one of effective methods for enhancing oil recovery during chemical flooding. Aiming at this practical requirement, we do some researches into physical simulation research of flooding efficiency on alternative injection of polymer and alkaline-surfactant mixture. The experiment results show that the increasing amplitude of enhanced oil recovery of model chemical flooding will reach by 30% when we adopt alternative injection of polymer and alkaline-surfactant mixture to do oil displacement experiment. The experiment results also show that appropriately improving the injection speed of alkaline-surfactant mixture (It is suitable to no more than the injection pressure value of previous polymer slugs) can help enlarge conformence efficiency, and then enhance oil recovery. But we can't inject too quickly, otherwise alkaline-surfactant mixture will break through previous polymer slug along with high permeable bed and reduce oil displacement effect of middle and low permeable bed.