Abstract: Oil and gas shows are found in bedrock outcrop and bedrock reservoirs are discovered by drilling in Liyuan area of Biyang Depression. Studying its geological conditions and hydrocarbon accumulation process is of great significance for guiding oil and gas exploration in sags. Based on outcrop, seismic, drilling, logging, mud logging core, and geochemical data, the oil and gas accumulation factors and formation process of bedrock pools in Liyuan area are analyzed. It is considered that the oil and gas formed in the hydrocarbon–generating depression of the Hetaoyuan Formation migrated into bedrock and accumulated in the nose–like tectonic setting through the fault–sand complex transport system. The overlying Gushantou Formation schist, boundary fault gouge, upper wall shale and stable hydrodynamic conditions provide effective capping for oil and gas. The marble of Caijiawa Formation of Dahe Group in Mesoproterozoic developed high–angle shear fracture and dissolution hole under the action of structure. The pore permeability is good and it is the main bedrock reservoir. The analysis of hydrocarbon forming model of bedrock reservoirs in Liyuan area can provide reference for hydrocarbon exploration of bedrock reservoirs in the same type of fault basins.