Research on high-velocity bullet impact resistance of composite plates has been widely used in bulletproof material field, but limited studies have focused on the response of composite plate under low velocity and large fragment impact. In this paper, the impact response of polyurea-coated ceramic-aluminum composite plate to low velocity and large mass fragment was experimentally and numerically studied. The fragments were launched using a self-designed launcher, which can realize the free flip impact test of low velocity and large mass fragments with flight speed of 100–300 m/s and the mass of 0–100 g. Based on finite element method and smooth particle hydrodynamics, the impact model of low-velocity large fragments on composite plates was established to study fragment deformation and composite plate damage and compared with the experimental results to verify the effectiveness of the model. The multi-angle impact response of the fragment on the composite plate was studied. Results indicated that unlike the high-velocity impact of traditional bullets, low-velocity and large-mass fragments will flip in varying degrees after hitting the target accompanied by the deformation of the fragments, which remarkably influence the impact penetration ability of the fragments. Moreover, with the increase of biting angle, the composite plates show enhanced energy absorption capacity.