This study focuses on the impact damage and residual strength of composite sandwich structures, which is carried out in-depth due to its significant importance in the engineering field. The composite laminate consists of a carbon fiber face sheet and a foam core. Considering the differences in material properties between the two, comprehensive modeling is necessary. In this study, the PUR FR—6710 foam material is adopted, and it is assumed to be isotropic. Its mechanical properties exhibit three stages during compression, including linear elasticity at low stress, a yield plateau when the cell walls are crushed, and densification of the material. Moreover, plastic and failure behaviors occur during impact, which are defined by the crushable foam model. For the fiber material, it is assumed that there is no plastic strain in the warp and weft directions, and plastic strain only occurs in the in—plane shear direction. The in—plane shear plastic problem of the composite single layer is dealt with by combining the plastic theory and the damage theory. The maximum stress criterion is used to judge the fiber tensile and compressive failure modes.