Abstract: The effect of thermal properties on performance was determined for the headstock of a CNC lathe. Based on the factors needed for finite element analysis (FEA), an FEA model of the headstock was established, with the constant temperature field distribution and thermal equilibrium time of the headstock simulated and calculated. Under conditions of heat and structure load, the temperature field and thermal deformation of the headstock were calculated using a thermal and structure coupling technique, and heat distortion trends of the spindle assembly and headstock were analyzed. Results indicated that hot asymmetry affected machine processing performance and provide a foundation for optimization design of spindle assembly and thermal error compensation.