Abstract: Production declines rapidly after putting the polymer-flooded Unit Ⅱ in the second interval of the Hetaoyuan Formation in Xiaermen oilfield into waterflooding agaia To solve this problem, several measures are applied including performing layered water injection timely in injectors, profile correction in injectors, water plugging in oil wells, putting more reserves in low permeability reservoirs into production, controlling the up going of composite water cut, and slowing down production declining. Real effects are better than expected.