In order to enhance the ability of tank's active protection against the rod armor-piercing projectile, a rotary-cutting frisbee was proposed, which intercepts the rod armor-piercing projectile through the head-on collision or rotating swipe. The factors that affect the penetration of rod armor-piercing projectile were analyzed; the finite element model was established to simulate how the rotary-cutting frisbee intercepts the rod armor-piercing projectile. Research shows that rotary-cutting frisbee can cause the rod armor-piercing projectile's deformation and damage and reduce the rod armor-piercing projectile's target velocity, and deflection, these impacts will reduce rod armor piercing projectile's penetration power, even cause it miss its target.