Abstract: Based on the failure of a tank gun to launch a stabilizer blast bomb with tail fin, this paper analyzes the possible causes of the failure, and obtains the minimum chamber pressure to meet the opening condition of tail fin. The fault tree of near-projectile was established and qualitatively analyzed, then the fault patterns were checked one by one according to the fault trees. The failure mode of insufficient chamber pressure which may cause flight failure of tail fin projectile was not determined in the course of the investigation, the simulation of chamber pressure of mixed charge was carried out by Matlab software. It was verified that the reason for the tail projectile near the shell was the inadequate mixing ratio of the charge. Taking muzzle velocity and chamber pressure as the object of investigation, the optimum design of charge scheme under mixed charge conditions was carried out by Matlab software. The test verifies that the kill bomb with optimum charge scheme can fly normally.