As one of the important factors affecting the comprehensive performance of high-speed motorized spindle unit, the study on the heating mechanism of angular contact ball bearing is particularly critical and important. Therefore, this paper will start from the heating mechanism of angular contact ball bearings, comprehensively consider the interaction between the rolling body and raceway, cage, lubricant and the influence of elastic deformation of rolling body. Firstly, the quasi-dynamic model of the bearing is established, and the calorific value of the bearing is calculated based on the method of ionizing heat source. Secondly, the influence of bearing skid phenomenon on bearing heating is analyzed. Finally, the calculated calorific energy is compared with the results calculated by Palmgren"s empirical formula for global thermal analysis. The analysis results show that skidding has a significant negative effect on bearing temperature rise at high speed, and proper preloading force can effectively prevent skidding and reduce temperature rise. The results of bearing calorific value calculated by the discrete heat source method and Palmgren method are in good agreement at medium and low speeds, and the discrete heat source method is obviously higher than Palmgren method at high speeds.