In order to solve the influence of thermal deformation on spindle life and machining accuracy, the temperature rise characteristics of high-speed motorized spindle was studied. Firstly, the thermal structure coupling model of motorized spindle was established, then the thermal simulation was carried out by using ANSYS software, and the distribution of steady-state temperature field and the thermal deformation of motorized spindle were analyzed. Finally, the influence of the change of spindle speed and cutting force on the temperature of motorized spindle was discussed. The results indicate that the method can effectively simulate the distribution of temperature field and thermal deformation in the working process of the motorized spindle, and the simulation results are basically consistent with the experimental results, which provide a reference for the temperature control of the motorized spindle.