Abstract: The Silurian Longmaxi Formation Shale is extensively developed in the Weiyuan and West Chongqing areas of the Sichuan Basin. The characteristics of the shale pore structure in the areas are quantitatively studied. With the shale samples in the Weiyuan and West Chongqing areas as examples, the characteristics of the pore structure and the pore size distribution of the reservoir are determined by using experimental techniques such as the carbon dioxide adsorption, the low-temperature nitrogen adsorption, and the high-pressure mercury injection. The results show that the development of micropores concerns mainly ones between 0.45 and 0.65 nm, the mesopores development concerns mainly ones between 2 and 5 nm, the macropores are relatively poorly developed and unevenly distributed, and the specific surface area is positively correlated with the micropores; the main pore type is the amorphous hole, such as an ink bottle hole with a wide neck, with a certain amount of parallel plate holes that are open to surrounding directions.