In order to obtain broadband light absorber, a compound structure model composed of graphene metamaterial layer, air layer and metal layer is designed. The transfer matrix formula is derived to compute the transmission characteristics of the designed structure. The results show that by adjustment of the structure parameters, wavelength bandwidth and angle bandwidth are expanded at the same time under the condition of high absorptance. For the incident angle π/4, the absorptance can achieve above 0.8 in the incident wavelength range of 0.1~6.0 μm. For the incident wavelength 3.5 μm, the absorptance can reach more than 0.9 in the incident angle range of -70° to 70°.