Abstract: Water and polymer cross-well pattern will cause water and polymer flooding interference, which will result in poor polymer flooding effect. In view of this problem, combining with the geological reservoir characteristics of typical offshore polymer injection oilfields, by using the numerical simulation software, the study on mechanism and influencing factors of water and polymer interference was carried out, and on this basis, corresponding adjustment strategies were made. Field tests show that by optimizing the sequence and intensity of water flooding, the water and polymer interference during the period of batch water flooding can be effectively controlled, and the benefit rate of oil wells can reach 86%. The net increase of oil production is 482.0 ×10~4 m~3, the recovery degree is increased by 5.1%. The effect of decreasing water and increasing oil is stable, and the development effect of polymer flooding can be improved.