Abstract: Based on the thermal explosion theory, the security of loaded projectiles penetrating into concrete targets was investigated. By taking the hot-spot temperature (also called the critical initial explosion temperature) as the initial explosion criterion, the thermal conductivity model was introduced. The relationship between the dimensionless heat flow density Qm and the dimensionless peak temperature Tmax, which were located in the interface between explosive charge and cartridge case, was acquired. The dimensionless control parameter Qmc, which can be used as the engineering criterion, and the dimensionless parameter KⅠ, which denotes the proportion of the received heat energy between explosive charge and cartridge case, were obtained. The results show that the intense friction between explosive charge and cartridge case is an important factor for the formation of hot spots which can cause projectiles to explode ahead of schedule.