Abstract: There are persistent problems of immature fracturing technology, unreasonable key parameters, and low production of single well after fracturing in deep shale gas horizontal wells in Southern Sichuan. This paper introduces a process for optimizing the fracturing process and key parameters based on laboratory evaluation and numerical simulation by combining the geological engineering characteristics of deep shale reservoirs in Southern Sichuan through comprehensive analysis of fracturing effect of fractured wells. It focuses on improving the complexity of fracture networks, increasing the volume of fracturing stimulation, and maintaining the long-term conductivity of fractures. The key technology of volumetric fracturing for deep shale gas horizontal wells that focuses on“dense stage+short cluster spacing, equal-holesize large hole perforation, sand fracturing with low viscosity slick water at high pumping rate, high strength proppant with small particle size combinations, and large-scale fracturing with high-strength”is formed. After the application of this technology in Well Z3, its production achieved the rate of 21.3×10⁴m³/d, which doubled and even more than that of wells with normal fracturing methods in the same block. In addition, high-yield production was achieved in several gas wells by applying this technology in deep shale gas horizontal wells in Southern Sichuan. This demonstrated that the technology has good adaptability and can be widely used. The successful application of this key technology in Southern Sichuan has laid a foundation for effective development of shale gas resources with depth around 3 500–4 500 m in Southern Sichuan.