In order to solve the problem of improving armor-piercing power in limited charge space, the influencing factors of small caliber multi-function projectile armor-piercing power are analyzed numerically. Taking the small caliber multi-function warhead as the object, the numerical simulation model is constructed. The influence of the variation of liner cone angle and the height of the charge on the armor-piercing power is analyzed by using the finite element software. Through the comparison of the numerical simulation and the simulation results, the factors affecting the armor-piercing power are obtained. The simulation results show that the cone angle of the liner and the charge height has great influence on the armor-piercing power of the small caliber multi-function warhead.