Abstract: Sandy bars are well developed in the near-shore area of the Huanghekou Sag for the Member D3 of BZ34 area. It is hard to get detailed description data of the reservoirs for their thin thickness and large burial depth. Through the study of the B Oilfield of BZ34 area, it is revealed that the development of thin sandy bars mainly depends upon the paleotopographic and paleo-hydrodynamic regimes. The sandy bar can usually be divided into three main types: far shore sandy bar, nearshore sandy bar and alongshore sandy bar, and the Member D3 of BZ34 area is dominated by the nearshore type between the average low tide and high tide lines. Upon the wedge-shape model, a positive linear correlation is found between the seismic wave amplitude value and the thickness of the sand bars. As the result, thickness can be semi-quantitatively predicted. The results from seismic wave amplitude is similar with those from paleotopographic study, and the two approaches could supplement each other in quantitative prediction of thicker sandy bars.