To study the effect of the dynamic characteristic of brake valve on full hydraulic braking system, the working principle of the tandem dual-circuit hydraulic brake valve was introduced, the mathematic model was established and the corresponding simulation model was set up based on software AMESim. The proportional property of brake pressure, the step response characteristic and the safety of dual-circuit compared to single-circuit were simulated, and then the corresponding experiment was designed to verify the simulation. The results show that the simulation model of the brake valve is accurate and the performance of the brake valve meets the request of full hydraulic braking system exactly. The optimized hydraulic brake valve controlling spring stiffness can be better adapted to the condition that the mass of load is of great difference between no-loaded and fully-loaded status.