Projectile impact test is carried out to investigate damage and failure behaviour under different impact velocity from 90m/s to 160m/s. Strain-time history curve on the control points are analysed in this paper. Sandwich beam dynamic response and the degree of structural degeneration under impact loading both depends on the thickness of metallic skins. The projectile impact test demonstrate difference damage characteristics between the sandwich beams with different thickness skins. The peak stress value are estimated approximately to determine the skin deformation and sandwich beam global damage degree.