A hydraulic transmission system of sprayer’s chassis was designed in view of the disadvantages of mechanical transmission system,such as complex structures,limited distribution and clearance etc.The design requirements and technical parameters of the whole sprayer were presented.The design scheme of the whole sprayer was described.According to the spraye〖BF〗r’s〖BFQ〗 function and requirements,the selection of hydraulic pump and motors were completed based on calculations.Then the hydraulic schematic was designed.In order to test the performance of hydraulic transmission system,the hydraulic system was simulated.The results show that the designed hydraulic transmission system meets the design requirements.The sprayer prototype’s testing in a farmland shows that the performance of hydraulic drive system of sprayer’s chassis is good.