Abstract: The hydrocarbon accumulation conditions of north sub-sag and central sub-sag in Liaoxi sag of Liaodong Bay depression was correlated and analyzed. It is recognized that the north sub-sag is characterized by large thickness of source rocks, high organic matter abundance, high maturity; the reservoirs are mostly sandstone with high-super high porosity, middle-high permeability, the mud cap rock has large single layer thickness and the overpressure is widely developed, the trap closure amplitude and area are large, the migration force is sufficient, the fluid is mainly transported vertically along the faults that are undeveloped in the late stage of tectonic movement, and the oil conservation condition is good. The central sub-sag is characterized by relatively small thickness of source rocks, medium organic matter abundance, low maturity; the reservoirs are dominated by sandstone with middle porosity and low permeability, the mud cap rock has small single layer thickness, the overpressure is locally developed, the trap closure amplitude and area are relatively small, the migration force is relatively weak, the transport system is complex, the fault in the late stage of tectonic movement is developed, which has a certain of damages to previous existing oil-gas reservoirs. The studied result indicates that the north and central sub-sags do have basic conditions for hydrocarbon accumulation, but the north sub-sag is better than the central sub-sag in reservoir-forming condition, hence it is a favorable area for petroleum exploration in Liaoxi sag