With the development of CNC machine tools toward high-precision, high-speed and greening, the advantages of lightweight CNC machines become more and more obvious. Taking ZN-XK2840 CNC gantry boring and milling machine as an example, this paper presents a lightweight design method of CNC machine tools based on particle damping technology. Firstly, the static property of the conventional CNC machine tool structure is analyzed by finite element method, the wall thickness is optimized, and the static property of the lightweight machine tool structure is analyzed to ensure that the maximum deformation and strength meet the requirements. Then analyze the dynamic property of conventional CNC machine tools such as modal characteristics, harmonic response. The particle damping technology can effectively reduce the vibration of the machine tool structure in the vibration transfer path. In this paper, through the establishment of particle system-gantry milling machine dynamics model, using discrete elemental dynamics software developed by ourselves to analyze the dynamic property of the machine tool with particle damper installed. By comparing with the dynamic property of conventional machine tools, it is found that the dynamic property of lightweight machine tool is better than conventional machine tools. According to the lightweight design, the gantry boring and milling machine with particle damper is installed. The acceleration amplitude and displacement amplitude are measured during the idling and milling process, which are all smaller than the conventional machine tools. Its weight is 53.8% lower than similar products, effectively reducing the weight.