Layered elastic metamaterials, which simultaneously exhibit negative effective mass density and bulk modulus, can be obtained with a unit cell of multiphase materials. In this paper, a systematic method for the design of multiphase layered elastic metamaterials is presented, and single objective along with multiobjective optimization models are proposed. Using the multiobjective genetic algorithm, the topologies of the layered periodic unit cell are designed for target frequency band structures characterizing negative wavenumbers. These obtained metamaterials with periodic unit cells can exhibit a negative refractive index in several frequency spectrums. This will be a reference for the design of 2/3-D elastic/acoustic negative refraction metamaterials.