To improve the power and the safety performance of the HEAT projectile, the charge quality of the melt-cast explosive and the matching relationship between the explosive and the warhead structure were studied. This study breaks through the limitations of the traditional method that based on the ideal composition between solid and liquid phases, and proposes a high-density charging method named “the match relationship between volumes and components”. It uses high density spherical RDX as its solid phase and DNAN as liquid phase carrier, with the volume of liquid carrier equal to the packing void of solid phase. Therefore, the internal defect of the charge is reduced, and the explosive energy is increased. Moreover, the structure of warhead of HEAT projectile was optimized according to the characteristics of the melt-cast explosive. In this study, RDX/DNAN instead of the traditional melt-cast explosive (composition B), is used to charge 105mm HEAT Projectile. The results showed that, compared with composition B, the explosive had fewer internal defects and better safety performance, with its density reached 98.3% of the theoretical density; the penetration depth of 105 mm HEAT projectile charged with RDX/DNAN was 11.9% greater than that of composition B; the penetration depth of the optimized HEAT projectile charged with RDX/DNAN was19.2% greater than that of composition B. It can be concluded that, when the HEAT projectile is charged with the melt-cast explosive, not only the charge density is increased with the charge defect decreased, but also the detonation property is improved.