Abstract: Adhesive layer performances have important influences on the protection capability of ceramic composite armors against a multi-hit. The numerical methods were founded to simulate the ceramics debonding of composite armors. Based on published ballistic experiments, for two different adhesives epoxy and polyurethane, the material and thickness effects to the protection capability of ceramic/aluminum composite armors against a single hit and two hits were numerically investigated. The results show that the method without setting an adhesive layer may be employed to study a single impact, but in the condition of a multi-hit, the method with setting adhesive layers should be adopted. When against a single impact, the limit velocity of composite armors increases as the adhesive layers getting thinner. The polyurethane adhesive layer should be used in composite armors against a multi-hit and its better thickness is about 0.4 mm when the composite armors against two hits.