<p>This paper proposes a multiscale topology optimization method for the design of functionally graded lattice structures for energy absorption, considering material nonlinearity. The proposed multiscale topology optimization procedure consists of pre-processing, main processing, and post-processing. In the pre-processing step, the Representative Volume Element (RVE) method is used to compute the effective material properties. To consider material nonlinearity in the effective material property calculation process, the bilinear hardening model is applied. In the main processing step, multiscale topology optimization is performed using the computed effective material properties to maximize energy absorption performance until fracture occurs. Finally, in the post-processing step, the optimized design variables are reconstructed into a functionally graded lattice structure. Through a design example, the effectiveness of the proposed method is verified, and the topology optimization results are converted into a CAD format and fabricated using 3D printing to confirm manufacturability.</p>