Abstract: By taking the polymer flooding example of three kinds of oil layers in La 8-182 well area of Lamadian oilfield, the effect studies of geological factors, such as sedimentary types of sand bodies, reservoir parameters, and micro structure upon polymer flooding have been carried out. The results indicate the producing degree is the highest in underwater distributary channel and cuspate-shaped sand, and the lowest in non sand sheet. Affected by reservoir parameters, the bigger the sand body thickness of single layer is, the bigger the permeability and the higher producing degree of polymer flooding are. Affected by microscopic structural types, the polymer flooding effect of positive and oblique microscopic structural types are obviously better than negative microscopic structural type.