Abstract: This paper aims to improve uneven reservoir utilization in polymer flooding development and effectively exploit unutilized remaining oil in thick reservoir. Taking polymer flooding block A of X oilfield as the research object, based on reservoir physical properties, combined with reservoir operation status, the identification standard of ultra-high water cut was established. For the thick oil layer, the perforation method of "evading + replenishment" is conducted, which means avoiding perforating the ultra-high water cut section in the early stage of production, then perforating the ones that have been evaded in the early stage of water cut recovery, so as to continue the cluster flooding development. Studies have shown that for the thick oil layer with no isolation layer: type I avoiding shooting wells have the lowest recovery rates, while type II has the highest recovery rates. Non-avoiding shooting wells have the recovery rates in between. For the same type of reservoir, regardless of thick reservoir with or without spacer, it is beneficial to improve oil recovery by preferentially shooting off the bottom reservoir. The results of this study have been applied to other polymer flooding blocks and works well, which provides valuable experience for polymer flooding development.