The thesis aims at exploring the perforation of double-layered plates in contact struck by a blunt rigid projectile.The experiment shows that the ballistic limit of a double-layered target is higher than a monolithic target’s.The thesis considers that the higher ballistic limit lies in the great bending deformation which requires moreenergy consumptions and the plug has extended the effective thickness of target.Based on the laws of conservation of energy and the model of Chen and Li,the calculation formula of residual velocity can be put forward after the blunt projectile penetrates the double-layered plate.In the process of armor-piercing, considering about the influence of the plug on the property of terminal ballistic limit,the thesis has compared and analyzed the relevant experimental data about blunt projectile piercing the plates from Weldox 700E series