Abstract: Under the combined influence of internal and external heat sources, machine tools undergo thermal deformation, which seriously affects their positioning and geometric accuracy. Effectively suppressing machine tool thermal errors is a significant research area. Firstly, based on the study of thermal deformation patterns of linear axes with different support structures, a structural optimization design method for machine tool linear axes was proposed. The optimized linear axis structure can automatically adjust the ball screw preload to meet the pre-tension requirements under varying temperature conditions, while its support structure features an adjustable design that can be configured into any installation configuration according to the machine tool's thermal deformation status. Subsequently, practical tests were conducted on two domestic three-axis vertical machining centers to compare and validate whether the thermal deformation directions of the linear axis and the spindle were consistent before and after the structural optimization, under different installation configurations of the linear axis. Finally, the actual machining performance of the machine tool after the structural optimization design improvements was validated through cutting tests on workpieces. The results demonstrated a significant improvement in the process capability index for batch machining of workpieces on the machine tool equipped with the optimized structural design.