Abstract: In order to realize the dynamic numerical simulation of the whole braking process for a high-speed train, a fluid-solid coupling model of the aerodynamics brake panel was established based on the smoothed particle hydrodynamics(SPH) method. The motion, the force distribution and the variation of aerodynamic drag during the braking process were explored. Results show that under the conditions of the speed of 300 km/h and the maximum opening angle of 90°, the time of the whole opening process is about 0.025 s, which meets the requirement of a quick response in emergency braking. In the initial stage of the brake panel opening, the force mutates with a gradient distribution, so that the brake panel is easy to bend and deform. During braking, the force level of the brake plate suffered increases gradually and remains evenly distributed. The edge of the right angle bears more force than other areas due to air drag, so the brake panel is more effective. Furthermore, the maximum aerodynamic braking force appears at 75°~85°, rather than at a vertical position. The maximum opening angle of the brake panel is suggested to be set at 80° to produce the maximum aerodynamic braking force.