In this letter, a novel synthesis method for broadband multilayer absorber based on multi-objective genetic algorithm (MOGA) is proposed. The inhomogeneous medium can be equivalent to homogeneous medium using the effective medium theory, and the absorption of the multilayer inhomogeneous medium absorber can be calculated. A MOGA is introduced to optimize the geometric parameters of the multilayer inhomogeneous medium absorber. Compared with the design results of two existing methods, the total thickness of the structure designed using the MOGA synthesis method is reduced by 10.8% and 9.1%. In addition, a broadband and wide-angle absorber with 90% absorption bandwidth covering 2–18 GHz is designed using this method, and the total thickness is only 0.133 wavelength and has excellent oblique incidence stability, which has potential uses in microwave and visible light applications.