Abstract: The axle-box bearing is a key component of high-speed trains， and the wheel-rail excitation caused by complex braking conditions leads to extremely complex vibration and contact characteristics of axle-box bearings and it is unclear until now. Therefore， a rigid-flexible coupled dynamics model of a high-speed train considering braking systems and axle-box bearings is established. Moreover， the braking system， axle-box bearing and vehicle system are dynamically coupled via the nonlinear friction of the braking interface， wheel-rail interactions， nonlinear contact of the axle-box bearing and suspension systems. Further， the field tests are conducted to verify the effectiveness of the established model. Based on this， the vibrations， bearing internal force， and contact characteristics of axle-box bearings under different braking conditions are systematically studied. The results indicate that train braking increases the longitudinal force of the axle-box bearings on the first and second wheel-set， and enhances the longitudinal vibration. The vertical vibration of the axle-box is slightly influenced by braking. In addition， when the train brakes， the friction between disc and pad makes the pitch motion for bogie frame， causing changes in the primary suspension force on the first and second wheel-set， resulting in a decrease in the vertical force of axle-box bearing on the first wheel-set， an increase in the vertical force of the axle-box bearing on the second wheel-set， and ultimately an increase in the maximum roller-raceway and contact stress of the axle-box bearing on the second wheel-set.