Abstract: Keshen 10 gas reservoir, developed in Kelasu structural belt in Tarim Basin, is an ultra-deep tight sandstone gas reservoir, which shows complex drilling conditions, low natural production capacity and great challenge in increasing well production. In order to improve the benefits of gas exploration and development, geomechanic analysis such as the current in-situ stress field and fracture activity is conducted on the basis of geological study, which enables to determine the distribution law of the current in-situ stress field and fracture activity of Keshen 10 gas reservoir, and identify great variation in permeability of fractures with different directions. Then the fracturing results are analyzed of various well trajectories with different well types and deviations, and the geology and engineering integrated working method is proposed to guide the optimization of well trajectory design. The results show that: (1) Different from the medium-shallow gas reservoirs, well production capacity is distinctly affected by the current in-situ stress and its induced fracture activity of the ultra-deep gas reservoir, and it is indicated that low current in-situ stress and active fractures are conducive to the high production of gas wells; (2) The current in-situ stress, fracture characteristics, wellbore stability and the propagation of fracture network vary greatly in various parts of the ultra-deep reservoir, therefore,the highly deviated wells have more advantages in drilling safety, drilling rate of the low in-situ stress areas and high angle fractures, as well as better fracturing results than wertical wells, and the practice shows that the high-yield production can be obtained by a favorable wellbore trajectory when effectively dealing with the strong heterogeneity of the ultra-deep tight sandstone gas reservoir; (3) The current in-situ stress field modeling based fracture activity analysis, wellbore stability prediction and fracture network simulation are the key technologies in geology and engineering integrated fracturing engineering, which are conducive to the optimization of wellbore trajectory and optimal selection of fracturing method and intervals; (4) The geology and engineering integrated working method supports to build a bridge between geological study and engineering construction, which plays a positive role in well stimulation of ultra-deep gas reservoir and improving the benefits of ultra-deep oil and gas exploration and development.