Abstract: Reservoir types in the complex fault block oilfield in the northern slope of Biyang depression mainly are fault nose, fault block and fault plus lithologic reservoirs. Hydrocarbons mainly accumulate in the fault nose block of the nose structure. Analysis on the controlling factors of hydrocarbon accumulation in the study area reveals that inherited nose structures control the direction of hydrocarbon accumulation and abundance, while the oil - bearing area and the height of hydrocarbon column are mainly controlled by sealing capacity and degree of faults, and hydrocarbon distribution patterns are under the control of the structural modes of various fault block groups associated with elongated structures.