Field survey reveals that the Daping Dengying Formation Paleoreservoir can be classified as fracture reservoirs. It is controlled by the detachment structure, with fractures mainly developed in the upper part of the Dengying Formation. A large volume of bitumen is filled in fractures, with minor distributed along the suture line or permeated through the surrounding dolomite. The analysis shows that the δ 13Corg and V/(V+Ni) values of the bitumen are -3327‰ and 089 respectively, which are close to that of the Niutitang Formation shales, indicating that the paleooil reservoir likely sourced from the source rocks of slop belt and basin in the Cambrian Niutitang Formation. The homogenization temperatures and the Raman compositions of fluid inclusions in quartz or calcite vein fractures in the paleoreservoirs show that since middle Jurassic period, the paleoreservoirs have experienced fractures formation, hydrocarbon charging, destruction and underground fluid permeation. Our study shows that the Sinian Dengying Formation in the SangzhiShimen synclinorium in north of paleooil reservoir has a burial depth of nearly 4 kilometer, which formed well preservation conditions for oil and gas. In addition, differences of lithology above or below the detachement belt caused fracture development of the Dengying Formation, which has distinct improvement for reservoirs and be of possibility to form the secondary petroleum reservoirs.