In recent years, multiple high-yield industrial gas flow wells have been drilled in the Maokou Formation of Hechuan-Tongnan Block, indicating its enormous resource. However, due to the overall low level of exploration in the region, the genesis and main controlling factors of reservoirs are still unclear, making reservoir evaluation and prediction difficult. Based on data from 8 drilling wells,reservoir characteristics analysis was conducted using core, thin section, imaging logging, pore permeability data, and elemental geochemistry. The results show that: ①The Mao-2 Formation mainly develops grain dolomite, calcareous dolomite, Calcium containing dolomite, and granular limestone. Among them, grain dolomite is the main carrier of reservoir space, mainly composed of dissolution fractures and caves, with a small amount of intergranular dissolution pores developed; A small amount of granular limestone reservoir, with the main storage space being dissolution pores and fractures.②Vertically, the Mao-2 Formation exhibits obvious karst zoning characteristics, with U–Pb isotope ages (261.1–262.8 Ma) indicating the development of karst processes during the contemporaneous period. The subsurface flow zone forms a large karst fissure system, and the sediments in the fissure system are likely to undergo dolomitization. Element geochemical analysis shows that dolomite has a lower degree of dolomite ordering, and its rare earth element distribution pattern is similar to limestone. The diagenetic fluid is locally restricted seawater.③Affected by karstification, the granular limestone in the subsurface flow zone and the surrounding area of the granular beach undergoes selective dissolution, forming granular dissolution pores and intergranular dissolution pores. Fluid transformation forms dissolution pores and fractures to improve the physical properties of the granular limestone, forming a granular limestone reservoir.④The development of dolomite reservoirs in the Mao-2 Formation is mainly controlled by five factors: ancient landforms and sedimentary facies, contemporaneous karst, early dolomitization, and hydrothermal dissolution related to the Emei Rift Movement. The main location for the development of high-quality reservoirs is the overlapping of contemporaneous faults in high areas of ancient landforms. The second section of the Maokou Formation reservoir can be further subdivided into dissolution fissure type dolomite reservoir, dissolution fissure pore type transitional lithology reservoir, and dissolution fissure pore fracture type limestone reservoir, with clear porosity boundaries among the three. The research results provide a basis for predicting the porosity of different types of reservoirs in the Mao-2 Formation in the study area, and effectively guide the exploration and deployment work in the study area.