Abstract: The ceramic/ultra-high molecular weight polyethylene (UHMWPE) composite armor plate is widely used in the ballistic protection field because of its excellent performance of light weight and high strength. It dissipates the kinetic energy of the projectile through the breaking of the ceramic and the deformation of the back plate. The energy absorption of ceramic fragmentation is the main mode of dissipating kinetic energy of armor piercing projectile. Therefore, it is important to analyze the fracture process and damage evolution characteristics of ceramic to optimize the protective performance of ceramic composite armor. The B₄C was used as panel material, and UHMWPE laminate was used as back plate material. B₄C/UHMWPE composite armor plate was prepared by resin film infusion. The composite armor plate was impacted by 54-types 12.7 mm armor piercing projectile at the velocity of (488±10) m/s to study the anti-penetration performance. Based on X-ray computed tomography (CT) technology and fracture morphology observation, the ballistic response mechanism of composite armor plate was analyzed. Further, the fragmentation behavior and characteristic parameters of B₄C ceramics were explored. The results show that the damage region of B₄C ceramics presents a double cone shape. The response region of the ceramic includes the advanced fragmentation zone on the back face of the ceramic plate, the remaining ceramic plate after ballistic penetration, and the fragment-complete pulverization zone directly below the projectile. There is an obvious positive correlation between the free surface cone angle of B₄C ceramics and the anti-penetration performance of composite armor plate. The response process of B₄C/UHMWPE composite armor plate includes shock wave propagation process and the generation of free surface formation in ceramics, B₄C ceramic fragmentation process, and the coupling process of compression, shear, and tension of UHMWPE laminate.