///Based on biomarker parameters and carbon isotopes, three types of oils and two settings of hydrocarbon-sourced groups in the Liushagang Formation are classified. According to oil-to-source correlation, the oil sources of the concealed reservoirs in the first and the second members of Liushagang Formation of the Weixinan sag are determined. They are generated from different hydrocarbon-sourced groups. Based on contacting relationship between concealed traps and source rocks, two patterns of oil entrapments for different reservoirs, i.e., parastructural and paralithologcal reservoirs have different accumulation features and controlling factors. For the concealed reservoirs in the first and the second member of Liushagang Formation, it is different in source rock, conducting system and oil filling pattern.