In order to enhance the electromagnetic wave absorption efficiency of composite materials with laminated structure and to investigate the effect of electromagnetic structure on wave absorption performance. Resin matrix composites containing magnetic electromagnetic wave absorbents were prepared by molding process. The electromagnetic parameters of the composites were analyzed using coaxial method, while the reflectance was tested by the bow-frame measurement method. The experimental results proved that the simulation calculation of the wave absorption properties of composites using electromagnetic parameters as inputs is feasible. Then the electromagnetic structures of composites are optimized for lay-up design. The design solution with the best wave absorption performance is selected by simulation calculations, and the reflectance testing of the composites demonstrated the effective optimization of the lay-up design. The results indicate that the composites with a single absorbent content have poor absorption performance, but the effective absorption bandwidth can reach 9.65 GHz after the lay-up design. The optimization of the electromagnetic structure of the composites can significantly improve its wave absorption performance.