This article explores practical applications of lightweight design for green machine tools in response to global carbon policies and ISO 14955 standards. By integrating structural geometry optimization, topology optimization, and manufacturing direction constraints, it achieves lightweight yet high-stiffness designs to reduce energy consumption and carbon emissions. The study also introduces composite-metal hybrid structures to enhance rigidity and damping while reducing weight and energy use. These innovations aim to accelerate the green transformation of the machine tool industry and strengthen its global competitiveness.