Abstract: The Tarim Keshen 9 Gas Field shows the typical characteristics of ultra-deep, high temperature and high pressure environments. During the drilling process, challenges such as complex geological structures, long drilling period, the coexistence of high-pressure saline and weak leakage layers in the salt-gypsum layer, difficulty in the anti-slanting and rapid drilling of high steep post-salt strata, and low ROP in the Jedick formation and tight sandstone reservoir. To overcome the problems, vertical drilling tools and optimized high-efficiency PDC bit were piloted in the post-salt strata; high-density oil-based drilling fluid, pressure management water drainage and safe drilling technologies were used in the salt-gypsum layer; 360° rotating teeth bit, turbine + impregnated bit speed-up drilling technologies were used in tight sandstone reservoirs. The combination of the above technologies constituted the key drilling technologies for complex ultra-deep wells in the Tarim Keshen 9 Gas Field. Those key technologies achieved significant field application effects. The average drilling period in the Keshen 9 Gas Field was reduced by 12.0%, the accident complex time efficiency was reduced by 4.1%, and the average ROP was increased by 13.0%. The results showed that the key technology of complex ultra-deep well drilling had high application value to increase the drilling speed and reduce the complexity in Keshen 9 Gas Field