The Longmaxi Formation shale with a depth of more than 3,500 m in southeastern Sichuan has a wide distribution range and abundant shale gas resources. It is of great commercial value to carry out efficient fracturing and transformation to obtain high and stable shale gas. The triaxial compression test was carried out on the rock by setting different temperature and confining pressure experimental conditions. The stress-strain characteristics, peak strain and peak strength, brittleness and fracture mode of the rock under different buried depth conditions were analyzed. The experimental results show that the peak strain and peak strength of shale increase from 0.54% and 173.0MP to 1.14% and 107.8MPa during the burial depth from 2044m to 4388m. With the increase of buried depth, the brittleness index of shale decreases, and the fracture degree and fracture mode of rock transition from complex split type to single shear type. Combined with the previous research results，it is considered that the lower limit of buried depth of shale with brittle mineral content of 60%~ 65% is 4400 m, which is close to the lower limit of buried depth of deep shale gas reservoir and the upper limit of ductile zone of rock mechanics, and the Longmaxi Formation with a buried depth less than this range is a favorable fracturing target under the current technical conditions. It is suggested that the pretreated acid solution with optimized proportion should be used to acidify the rock. Liquid nitrogen vaporization fracturing technology is considered in the fracturing process. Fully drill in dense areas where natural fractures develop and use multi-scale particle size proppants to fill and support more levels of fractures.