When braking is applied to a heavy-haul train, the dynamic behavior of the train becomes more complex compared to when there is no braking, which poses significant challenges to the safety of train operations. In order to study the vehicle dynamics behavior at the maximum coupler force of a heavy-haul train under emergency braking conditions, a vehicle-track and longitudinal-vertical coupled dynamic model, considering the effects of shoe friction braking, is established with a 25 t axle heavy-haul wagon from China as the research object. On this basis, this study systematically examines the impact of varying running speeds and adhesion conditions on the dynamic wheel-rail interaction and vehicle vibration response during emergency braking. The results show that under braking conditions, the brake shoe pressure and longitudinal coupler force exacerbate the wheel-rail dynamic interaction and cause changes in the displacement of the under-rail structure. The low adhesion condition has a significant effect on the longitudinal interaction of the wheelsets, leading to a sharp increase in the longitudinal creep rate and wear number, thus increasing the risk of wheel slip and wear. This effect is more pronounced at low speeds. Moreover, the low adhesion condition and longitudinal coupler force significantly affect both the rotational and longitudinal motion of the wheelsets, leading to increased wheelset vibration and deterioration of vehicle dynamics.