The invention relates to a composite structure armor plate and a preparation method thereof, and belongs to the field of armor protection. The composite structure armor plate mainly comprises a ceramic layer, a fiber material stacking layer, a metal layer and a back plate. According to the integral connection relation, a metal plate is assembled on the surface of the back plate in a seamless manner to form the metal layer; the fiber material stacking layer is flatly laid on the surface of the metal layer; a ceramic plate is assembled on the surface of the fiber material stacking layer in a seamless manner to form the ceramic layer; and all the layers are bonded through a thermosetting or thermoplastic adhesive. The fiber material stacking layer is formed by stacking a plurality of fiber material single layers, and if the fiber material single layers have the specific fiber orientation, the fiber directions of the adjacent fiber material single layers are perpendicular to one another. The composite structure armor plate has high multi-bullet hitting resisting capacity, the self weight and thickness are reduced through a large number of ceramic and fiber materials, and the composite structure armor plate is relatively light under the same bulletproof level, can be widely applied to the field of light bulletproof armor and achieves effective protection.