Early variable speed pump has advantages including simple structure, compact, easy to In order to verify whether the designed structure met performance requirements, a matching test bench was designed and manufactured, enabling performance evaluation to pumps and valves in lab.install, less external tubing which is the board structure outside the gearbox, but the disadvantages are early grinding pump casing, noisy, poor reliability, shorter life etc, affecting the performance of the host. A variable pump structure was improved, which was placed inside the transmission. A locating bearing was increased,so the casing scraper was weakened, the noise was reduced and service life could be prolonged. At the same time, the oil outlet relief valve and the converter back pressure valve were combinated to the gear pump, so its structure became more simple and compact. Besides having the functions of hydraulic oil suction, converting mechanical energy into hydraulic energy,it had the functions of controlling gearbox hydraulic system pressure and torque converter working pressure.