Head injury has become a primary threat to our life in transportation accidents,construction and sports.However,birds can protect their brains from injury during their pecking.In order to reveal the underlying secret,chicken and pigeon were chosen to test their pecking force and frequency.The kinetic energy density,defined as the ratio of impact strength and brain mass,was calculated to compare the shock resistance of the birds and human being.The result shows that the shock resistance of the birds is much higher than human being.Finite element models of chicken head and pigeon head were established using reverse engineering method to conduct the numerical analysis of their heads impact response.The numerical results show that the stress wave in their heads propagates mainly through the lower beak rather than the upper beak directly to back skull.This is because the skeleton structure of the upper beak is filled with viscoelastic soft tissue,which can retard the propagation of the stress wave.The stress wave was directed by the propagation path,avoiding the damage of the brain.The biomechanical design,setting a propagation path for stress wave,may inspire new approaches to improve and design anti-impact equipment.