Abstract: A protective plate includes a first composite layer having a thickness of d1 in mm, a metal substrate, and a second composite layer having a thickness of d2 in mm that are sequentially stacked, where d1>0, and d2?0. The first composite layer and the second composite layer each includes a polymer base material and a reinforcing material, the reinforcing material includes nanoparticles, the first composite layer has a tensile strength of ?1 in MPa, the second composite layer has a tensile strength of ?2 in MPa, the metal substrate has a thickness of d3 in mm and a tensile strength of ?3 in MPa, and the protection plate meets a formula: d 3 ( d 1 + d 2 ) + d 3 × ? 3 ( ? 1 + ? 1 ) + ? 3 > 0.032 .