Abstract: Composite structures have been widely used in the design of absorbing materials. However, the development of structural materials is challenged by the demand of broadband and efficient absorption performance. Herein, an impedance gradient microwave absorbing metastructure was designed and fabricated by fused deposition modeling of 3D printing technology. High dielectric loss composites were prepared by a mechanical blending of thermoplastic polyurethane and carbon black. Based on the reflectance formula of multilayer structure, the theoretical analysis model of impedance gradient structure was established. Calculation method of equivalent electromagnetic parameters, input impedance and reflectance of structure was derived. The designed impedance gradient structure can achieve −10 dB absorption bandwidth in the range of 2-18 GHz, and strong reflection loss of −20 dB can be achieved in the range of 2.68-18 GHz. The absorbing mechanism of the structure was further revealed by studying the distribution of electric field, magnetic field and power loss. The experimental results agree well with the simulation results. The impedance gradient structure designed in this paper provides a simple and promising route for broadband and wide-angle microwave strong absorption in practical application.