Experiments of steel tube confined concrete targets impacted by 12.7mm armor piercing projectile were firstly carried out, and then the depth formula of hard core projectile was established to explore the anti-projectile performance of steel tube confined concrete targets. The results show that the failure mode of steel tube confined concrete targets differs a lot from the failure mode of the unconfined concrete. The steel tube confined concrete targets develops hoop cracks on side face and works better in anti-projectile performance than the infinite concrete targets. Steel tube confined concrete targets also work well against multi-impact. 