The temperature field of the ball screw feed system of VMC vertical machining center was measured by thermal imager,the exponential function was fitted to the screw temperature data,and the modeling and calculation were carried out according to the principle of energy conservation to obtain the thermal boundary condition of the ball screw.The finite element analysis software Workbench was used to analyze the temperature variation of the ball screw in the machining center.The results were compared with the experimental data to verify the correctness of the calculation model of the convection heat transfer coefficient of the ball screw,and the convection calculated by the traditional empirical formula was corrected.It provides reference for the thermal analysis of the vertical machining center.