In this paper, the reservoir characteristics and fluid properties of a reservoir of the Bohai Sea oil field were taken as the research platform. It was confirmed that there exists compatibility between hydrophobically-associating-polymer (HAP) molecular aggregation and pore-throat size. The experiment for oil displacement in heterogeneous cores indicated that there exists applicability of HAP for a heterogeneous reservoir and the applicability can be influenced by polymer concentration. The experiment for oil displacement of parallel cores demonstrated the effect of polymer concentration on the applicability of HAP for reservoir heterogeneity from two aspects of the dynamic behavior of oil displacement and the effectiveness of oil displacement. The results show that with the increase of HAP concentration, the association degree between polymer molecules increases, molecular-clew dimension enlarges, and the compatible size of pore throats of the core increases. The change of HAP concentration not only has an effect on the amount of liquid suctioned by different permeability layers and on the time of profile inversion, but also has an effect on the displacement ability of polymer solution within different layers. As polymer concentration changes, the adaptability of HAP for reservoir heterogeneity changes and the oil-recovery efficiency also changes.