Abstract: The crossbeam, as the main supporting structural component of the CNC vertical lathe, undergoes deformation due to its own weight and external loads, which directly affects the machining accuracy of the machine tool. Therefore, it is necessary to perform lightweight and shaping design on it. Firstly, a finite element model is established based on the structural characteristics of the crossbeam of the CNC vertical lathe; then, its static characteristics and modal analysis are conducted based on actual operating conditions. Secondly, with the objective of minimizing the crossbeam's mass, the relative density method was used for topological optimization of the crossbeam. The structural locations for mass reduction were determined based on the material distribution results from the topological optimization and actual manufacturing process feasibility. Finally, the deformation compensation design method is used to perform shaping design on the topology-optimized crossbeam structure, resulting in the shaping machining curves required for the six crossbeam guide rail surfaces. Experimental results show that the optimized lathe crossbeam structure achieves a 5.35% reduction in mass, a 27.96% reduction in maximum deformation, and the first six natural frequencies were improved by 15.76%, 16.50%, 15.22%, 9.66%, 18.42%, and 14.69%, respectively. The optimized crossbeam achieved significant improvements in static and dynamic characteristics while realizing lightweight design. After contour machining, the straightness and alignment of the crossbeam guide rails met design requirements.