Abstract: In order to make a clear understanding of hydrocarbon accumulation characteristics and regularities in the western Bohai sea area,a study on the formation of Caofeidian-11 structure,a large-scale oilfield,in the eastern Shaleitian salient has been carried out.The study results indicated:1).Source rocks of Shahejie and Dongying formations in the southeast margin of Bozhong sag laid a good foundation for the formation of Caofeidian-11 structure;2).Hydrocarbon enrichment was controlled by NE faults activities in two phases.In late Jurassic-Cretaceous period,the left lateral activities of NE faults split the base and played a control role in structure formation of eastern and western members of Shaleitian salient.In Neogene period,the right lateral strikeslip fault activities of NE faults made the formations from a negative flower structure on the cover,which not only controlled the distribution of large drape anticline but also controlled the high point of the cover.3).The dominant migration pathways in Neocene period controlled the final position of large-scale oilfield.The hydrocarbon in Caofeidian-11 and Caofeidian-16 large-scale oilfields was formed along multiple dominant pathways and finally gathered in one direction.