The simulation analysis was made and the experimental verification was carried on the hydromechanical continuously variable transmission of the high clearance self propelled sprayer vehicles of indigenous design. The results show that engine speed, flow of speed control valves, pressure of main circuit and load torque are the main factors to influence the shift quality. Adopting the lower speed of engine，the lower pressure，the smaller load torque，and the larger flow can improve the shift quality as soon as possible. Agricultural spraying vehicles equipped hydromechanical transmission can not only achieve a continuous stepless change in speed, but also easy in operation, and reducing the labor intensity of the driver.