The intelligent brake test system's core is to establish the first vehicle brake pressure control model for different marshaling trains. A mathematical model of the first train tube in different marshaling trains is established based on the aerodynamic equation. The model takes into account the influence of the filling and exhaust of other vehicles on the tube pressure change of the first train. The brake valve's effective cross-sectional area is designed， calculated， and tested in a simulation using the established mathematical model. This provides a theoretical basis and technical guidance for developing new brake valves， as well as improving or repairing existing ones. To verify the accuracy of the model， test data obtained from the train brake test bench is compared and analyzed with the simulation results. The initial inflation data of the first train tube in long groups and the common brake pressure data were predicted and obtained.