Abstract：The bituminous fragments in Dengying Formation are described in this paper for the first time, and have been evidently defined as one of the Weng'an paleo-oil reservoirs. The reservoir is in the middle of Dengying Formation, the pores consist mainly of intercrystal, intercrystal dissolved and moldic pores and caves, being a middle-high porosity and high permeability reservoir. Based on an analysis of saturated hydrocarbon chromatography, biomarkers, and carbon isotopic composition of kerogen, the authors hold that the bitumen originated from Niutitang Formation source rock.