The high-speed motorized spindle,as the key component of machining centers and other high-end CNC machine tools,has performance directly affecting machining accuracy. According to the internal motor characteristics of the high speed motorized spindle in the paper,two major heat sources are analyzed and quantity of heat is calculated. The finite element analysis model of motorized spindle thermal characteristics is built through applying the ANSYS Workbench. The thermal steady state,heat-structure coupling characteristics is carried out based on the cooling coefficient of thermal boundary conditions,and taking heating value of the bearing and motor as thermal load,the temperature field distribution and thermal deformation of the spindle system are obtained, which prepare for the next thermal error modeling. The high-speed motorized spindle, as the key component of machining centers and other high-end CNC machine tools, has performance directly affecting machining accuracy. According to the internal motor characteristics of the high speed motorized spindle in the paper, two major heat sources The finite element analysis model of motorized spindle thermal characteristics is built through the ANSYS Workbench. The thermal steady state, heat-structure coupling characteristics is carried out on based on the cooling coefficient of thermal boundary conditions, and taking heating value of the bearing and motor as thermal load, the temperature field distribution and thermal deformation of the spindle system are obtained, which prepare for the next thermal error modeling.