The continuity velocity algorithm is widely used in SPH for high velocity impact simulation, but there is some error when calculating the separation between projectile and target. This paper adopts SPH frictionless contact algorithm to handle the contact problem in high velocity impact, and the perforation of a cylindrical steel projectile impacting a plate target is simulated in 3D. The corrected Johnson-Cook material model with damage effect and Gruneisen equation of state are adopted for the target. The SPH frictionless contact algorithm checks interpenetration between projectile and target using SPH neighborhood search, and contact force is enforced for contact particles. The comparisons between numerical simulations and experimental observations show that the SPH frictionless contact algorithm allow projectile and target to come together and separate in a physically correct manner.