A three-dimensional, vehicle–track coupled dynamics model has been developed that accurately reflects the dynamic performance of a high-speed train during operation. The model includes novel elements that allow detailed consideration of the transmission system and axle box bearings with gear time-varying mesh stiffness, bearing stiffness and bearing clearance. And then, it was extensively validated by comparing the results of the simulation with those of experimental tests. The temperature characteristics of the axle box bearing of the motor car and the trailer were analysed and the mathematical model was subsequently validated through long-term experimental field tests. The results indicated that the loads acting on the axle box bearing closest to the gearbox of the motor car (bearing 1) are significantly higher than those distant to the gearbox (bearing 2), the cause being differences in structural differences, which also lead to higher local temperatures. Conversely, when considering the trailer car, the dynamic performance and hence vibration and temperature of bearing 1 and bearing 2 were almost identical, this being a result of similarities in their structure and mounting arrangement. In summary, the temperature and vibration characteristics of axle box bearing can be used for its related assessment, design and maintenance.