For ignoring the influence of temperature on traditional research, this paper study the influence of high-pressure and high-temperature loads on the mechanical properties of welded steel cartridges. Using LS-DYNA software, a simulation model of the welding cartridge was established to analyze the impact of thermal shock on the steel cartridge during projectile launching. The results show that the temperature has a great influence on the residual stress of the cartridge, especially on the cartridge body, and also affects the shell release force, that increased about 16%. The results of this paper have important guiding significance for the steel cartridge case.