Abstract: The shale gas of the Cambrian Qiongzhusi Formation in the Sichuan Basin is an important shale gas replacement layer, which has the characteristics of ultra-deep, high stress, overpressure, high porosity, high TOC and high gas content. Compared with the Longmaxi Formation, the ultra-deep burial conditions bring more complex stress conditions, and the fracturing faces the difficulties of difficult crack propagation, simple fracture morphology, and unclear yield mechanism. In this paper, the numerical simulation of fracture initiation and the physical simulation of macro-meter-scale fracturing are analyzed by micro-fabric analysis. The fracture mechanism of multi-dominant minerals dominated by felsic minerals and the law of fracture extension under overpressure environment are clarified, and the mechanism of increasing production of complex fractures caused by lamina fracturing is clarified. Based on the seepage model of ' three fractures and three zones ', the ultra-deep fracture network volume fracturing technology of ' fine dessert optimization + ultra-high pressure and large displacement lamina activation + large-scale full fracture domain support ' is matched. The field practice shows that the laminae open to form fine cracks, form complex fracture networks, achieve the purpose of fully releasing production capacity, and achieve a high-yield effect of an average open-flow capacity of more than 2 million cubic meters after 15 wells, which provides theoretical support and technical path for the large-scale development of shale gas in Qiongzhusi Formation.