Abstract: As the main bearing structure, the CNC gantry beam is the focus of high stiffness and lightweight design. To achieve a lightweight design of the crossbeam, this paper employs the ANSYS simulation platform to perform static and dynamic analyses of two crossbeam structures and compares the corresponding results. The results show that the ten-type beam performs better than the rat cage type in terms of deformation, stress, and natural frequency, demonstrating significant optimization potential. Based on the response surface model and non-dominant ranking genetic algorithm, the beam mass is ultimately reduced by 335.5 kg, accounting for about 7.34% of the original weight, which provides a reference for the lightweight and high-performance design research of CNC machine tools.