To study the anti-penetration performance of composite armor with aluminum foam, based on the stress-wave propagation characteristics, a theorytical analysis of the structure of ceramic/aluminum foam/aluminum alloy composite armor was carried out. The energy absorption rule, residual velocity of jet head, and protective capability of armor under different dip angle were investigated from three aspects of different aluminum foam sandwich thickness, different thickness and arrangement way of front-back plate under the composite armor with same thickness, and composite armor dip angle. Results show that the aluminum foam as sandwich layer can reduce the particle velocity of back plate of composite armor adequately. Under the same dip angle θ, the particle velocity of back plate decreases with increasing thickness of aluminum foam. When the thickness of foam aluminum is 2.4 mm, the residual velocity of the jet head is minimum, the energy of the composite armor is maximum and the anti-penetration performance is optimal. Under the same thickness of aluminum foam, with increasing the thickness ratio t₁/t₂, the residual velocity of jet head of the interval and contact type composite armor decreases firstly, and then increases. When t₁/t₂=1, the anti-penetration performance of interval type composite armor is optimal. When the layout way is not the same only, the difference of penetration performance between interval and contact type composite armor is small. With increasing the dip angle θ, the protective capability of composite armor increases firstly, and then decreases. When the dip angle θ is 20°, the anti-jet penetration performance of composite armor is optimal.