Abstract: Qinnan depression is one of the depressions in offshore Bohai Bay Basin where exploration maturity is the lowest. The previous exploration effect of the depression was not satisfactory with its hydrocarbon sourcing capacity questioned. Source rock is more extensively distributed and more deeply buried in Dongwa and Zhongwa, the central areas of the depression, with a larger thickness. Therefore, the central part of the depression has a higher capacity for hydrocarbon sourcing and expulsion. The structural type of the depression controlled the direction of advantageous oil and gas migration. The steadily-distributed mudstone deposit of the second member of Dongying Formation controlled the oil and gas abundance level. The development locations and degrees of long-term active faults controlled the areas and abundance degrees of the Neogene hydrocarbon accumulations. There were mainly three accumulation patterns in the region – the selfsourcing and self-storing pattern, the early-sourcing and late –storing pattern and the lower-sourcing and upper-storing near-source pattern. The study indicates that the slope zone north of Shijiutuo uplift, the slope zone east of Qinnan uplift and the areas near QinnanⅠ fault and QinnanⅡ fault are the favorable exploration zones with a great potential for exploration.