Fault block M belongs to heavy oil reservoir with thick layer. How to further tap potential and improve oil recovery after entering polymer flooding development is particularly important. In the past, the influence of sweep volume and displacement efficiency on oil recovery has been the main concern in the theoretical study of enhanced oil recovery, while the contribution of sweep volume and displacement efficiency to enhanced oil recovery has been less studied. The characteristics of oil displacement efficiency and sweep volume in the polymer flooding process of M fault block were studied using the method of reservoir engineering which adopted the experimental method of indoor physical simulation, based on the relationship between resistance and oil saturation. And the contribution generated from oil displacement efficiency and sweep volume to enhance oil recovery was discussed. The results showed that the main contribution of polymer flooding was to enlarge the sweep volume of each layer. The contribution generated from the medium permeability layer to enhance oil recovery was 61.79%. And secondly, the contribution generated from high and extra⁃high permeability layer was 34.48%, while the low permeability layer was only 3.73%.