The paper discusses the performance of a hydraulic system controlling the shifting action of a construction vehicle transmission. Based on the principle of the hydraulic system of the transmission, a simulation model of the hydraulic system is established using AMEsim software. The simulation results indicate that the double-step hydraulic cylinder structure has an advantage of a fast, smooth and reliable shifting. The shifting connecting and separating overlap time of two clutches can be controlled precisely by an electronic joystick. The fast response speed can be ensured because using screw-in cartridge valves acting as the directional valves. Some techniques of improving the shifting quality are obtained. There is a great reference for the construction vehicles’ transmission in the future.