A sandwich plate with a truss core is composed of two face sheets and a truss core between the face sheets. In this paper, a metallic sandwich plate with a pyramidal truss core is investigated numerically, for its deformation and energy absorption ability under dynamic loading. To find the effect of mechanical properties on crashworthiness in the sandwich plate with a pyramidal truss core, various pyramidal cores were simulated and investigated. It appears that relative density and shear modulus of a pyramidal truss core effect the change of energy absorption.