Abstract: During polymer injection development in the Ng3-4 unit of the north of central region 2 of Gudao Oilfield, in order to improve the inner interference of layer, control injected polymer breakthrough, according to dynamic and static reservoir data, such as pressure fall-off curve, index curve of injection well, with the help of PI decision making technologies, profile control techniques before polymer injection are successfully applied to injection wells, which have low pore pressure and big pore passages. The application results have shown that the combination of inorganic grains, composite plugging agents and multiple slug combination profile control techniques is able to largely improve pressure drop index of water well and polymer flooding.