Abstract: Based on the geological, geophysical and well data, structural features, hydrocarbon accumulation and distribution patterns of the Dongying Formation in the Chengbei Sag are studied. The Chengbei fault and its branches controlled the distribution pattern of the Paleogene, and acted as the main oil migration path. However, the faults in the inner sag and on the southern slope are mostly the small interlayered faults difficult to form traps. Hydrocarbon accumulation systems consist of the southwestern gentle slope and the northeastern steep slope in the sag, and thus the structural and sedimentary combination is the main controlling factor of the hydrocarbon accumulation in the Dongying Formation. There is exploration potential in the structure-controlled reservoirs in the northern fault zone and the stratigraphic reservoirs in the southern gentle slope zone.