A fault system is one of the main geological factors controlling the formation and preservation of hydrocarbon reservoirs in Weibei Sag. The Weibei Sag is characterized by a complex fault system and multiple fault configurations. Unfortunately, previous studies had rarely focused on the overall fault systems and their controlling effect on hydrocarbon accumulation. Based on the seismic interpretation of the whole Weibei sag and geochemical data, the control of fault systems on hydrocarbon accumulation in this sag especially on the pathway of the sag was system atically studied. The following results were obtained:The faults can be grouped into 4 fault systems:NWW direction fault system, NW direction fault system, LiyuZaohu fault system and NNE direction fault system according to the fault strike. The fault configurations of the 4 fault systems mainly included strike-slip extensional fault configurations such as fault terrace type,“Y”-shaped type, anti-“Y”-shaped type and negative flower type. They were mostly formed in the extensional-rift period stage in which most faults of this sag were formed and influenced by several strike-slip extrusion. It was concluded that fault systems with different strikes played different rules in controlling hydrocarbon accumulation. The deep-rooted major faults exerted control effect on the distribution of gas fields and the evolution of the basin. The NW direction and NNE direction fault systems acted as the major pathways for hydrocarbon migration and indicated the direction of hydrocarbon，the Liyu-Zaohu fault system controlled the formation of most effective traps in the sag on account of it was on the dominant migration path and its good fault sealing and good reservoir property improved by minor faults.