Abstract: By analyzing the structural characteristics of No.4 sub-layer, the 5th sand set of the 3rd Member, Shahejie Formation (Es₃) in Dongxin Oilfield, a small fault in the southern part is determined as a reverse fault, making uplift in the north and depression in the south, which provides the trap condition for oil-gas accumulation. The study on the sand body and formation thickness indicates that the provenances are from the south, west and northeast rather than north. Finally, with analysis on the porosity, permeability and effective thickness of sand body, it is found that the most favorable exploration areas are the south and mid-west regions, followed by northeast region, while the mid-east region is of little significance for exploration.