In order to improve the effect of polymer flooding, different slugs were injected into the N development zone to optimize the slugs. In this paper, 25 million and 7 million molecular weight polymers of different concentrations were used to conduct indoor oil displacement test on the core, so as to determine the recovery factor, polymer consumption, water cut change and injection pressure change of each combination slug, and optimize the combination of slugs. The results show that high concentration polymer is helpful to the formation pressure holding and oil recovery, and can get lower water cut value and water cut value more quickly. High concentration polymer should be used for single polymer flooding, and at the same time, polymer can also be used for pre slug of combination slug. The same polymer with different concentration and three slug combination can get oil recovery closer to that of single slug. However, with the increase of the injection volume of the high concentration slug, the injection pressure increases obviously.In practice, it is better to consider comprehensively and choose the scheme with higher recovery, lower injection pressure and less polymer consumption.Compared with the single slug and the same polymer combination slug, different polymer combination slugs have more advantages in the comprehensive performance of recovery, polymer consumption, water cut minimum and injection pressure.