Based on the gas flow theory, according to the gas state equation and mass equation and the flow characteristics, the mathematical model of the re-inflation process of wagon brake system was established. Then, the model was verified on an intelligent simulation test platform. The experimental curve is basically in agreement with the simulation curve. The re-inflation process of the first and tail vehicles of 150 trains was investigated, and the variation characteristics of the vehicle reinflation mitigation process at different positions of the train were obtained, and the time difference between train tube and brake cylinder at different positions was tested.