Abstract: Taking the high-speed aerostatic spindle as the research subject, a thermal characteristic analysis was performed. Motor power losses and bearing friction losses were calculated, and the parameters of heat conduction and heat convection between the spindle and the external environment, as well as among the components of the spindle, were analyzed. A thermal-structural coupling simulation model of the electric spindle based on the finite element method was established using ANSYS Workbench. The influence of rotational speed, supply air temperature, and cooling water temperature on the overall temperature field of the spindle was analyzed, and the effect of thermal deformation of the spindle structure on the air film thickness was further investigated. The results indicate that thermal deformation has a significant impact on the air film thickness, necessitating further optimization of the cooling water parameters for the electric spindle.