In order to improve the service life of brake disc,the peak temperature,the maximum temperature difference and the instantaneous temperature difference of temperature increment per unit time of brake disc at different braking time when the vehicle speed changes were studied.The temperature field of the brake disc was simulated by using ADINA software and based on the thermalmechanical coupling model at a pressure of 0.5 MPa,and initial speeds of 140,160 and 180 km/h.The results show that the peak temperature and maximum temperature difference of the disc surface increase with the increase of initial speeds.The peak temperature of the disc surface reaches 151,167 and 200 ℃,the maximum temperature difference reaches 85,91 and 112 ℃ at three speeds.The temperature difference on the disc surface is mainly due to the distribution of the friction arc,and the increase of the initial speed enlarges the effect of the friction arc.The influence of initial speed on the temperature increment per unit time is mainly reflected at the initial stage of braking.In the later stage of braking,the temperature variation is mainly controlled by cooling conditions and heat conduction.The maximum axial temperature difference depends on the thermal conductivity of the disc,and it is not sensitive to the initial speed.