To study the multi-hit performance of steel-tube-confined concrete, experiments of thick steel-tube-confined concrete targets normally impacted by 12.7 mm armor piercing projectile were carried out, the damage modes and the depth of penetration were obtained, and the formula for multi-hit depth of penetration was established. The results show that: steel-tube-confined concrete targets of 300 mm in thickness can effectively resist armor piercing projectile for 3 times, and the penetration depth increment for the second and third impacts to their former impact are less than 20% and 10%, respectively; the formula for multi-hit penetration depth is in good agreement with that of experiment. Results are beneficial to the studies of anti-bullet structures and bursting layer structures of steeltube-confined concrete.