The electro-hydraulic brake valve is a key component in electro-hydraulic brake system of the wheeled construction vehicles. Its structure and performance parameters have great influence on the braking system. At present, foreign electro-hydraulic braking system used by the electro-hydraulic brake valve structurally similar to direct-acting proportional pressure-reducing valve which brake pressure can reach to 20MPa. In this paper, a domestic direct-acting proportional pressure-reducing valve whose pressure rating is 2.5MPa will be regarded as the research object. At the same time, we will use MATLAB / Simulink software to set up the dynamic simulation model of proportional pressure-reducing valve for the electro-hydraulic braking system and analyze the influence of the main structural parameters of the valve on system dynamic simulation. By improving the structural parameters, the brake pressure can meet the requirements of construction vehicle. This will provide a theoretical basis for the design and manufacture of the direct-acting proportional pressure-reducing valve which can be applied to the electro-hydraulic brake systems.