Abstract: The Member 4 of Sinian Dengying Formation gas reservoir in Gaoshiti block of Sichuan Basin is mainly controlled by the deposition of mound-shoal complex and epigenic karstification. Due to the cause of multi-factor superposition, there are some limitations in reservoir characterization of Member 4 of Dengying Formation according to the existing reservoir classification and evaluation criterion. Based on core observations, conventional and imaging log data analyses, CT core scanning and thin section identification, the karst reservoirs of Member 4 of Dengying Formation in Gaoshiti block can be divided into pore type, pore-vuggy type and fracture-vuggy type with matching reservoir spaces. Among them, the pore-vuggy and pore-vuggy reservoirs have the characteristics of good physical properties, easy exploitation and good pilot production, and are the high-quality reservoir type in Member 4 of Dengying Formation. In addition, on the basis of fine reservoir classification in single wells, application of conventional seismic reservoir prediction and ant tracking technology, as well as analyses of the dynamic data such as well test curves, production curves and open flow capacities of typical wells, the division scheme of gas well productivity can be established and the productivity models can be classified into three categories (Ⅰ, Ⅱ and Ⅲ) for Member 4 of Dengying Formation in Gaoshiti block. The high- quality reservoir has a high proportion in the productivity model Ⅰ and model Ⅱ, showing broad trough-shaped seismic reflection in the upper submember of Member 4 of Dengying Formation, well developed fracture-vuggy bodies in ant tracking attributes, and good effects during pilot production.