In order to solve the shortcomings of the traditional transmission mode of cotton picker in the picking process,such as the torque mismatch between the engine and the transmission parts,the cumbersome speed change process and the stumbling of gear shift,which cannot fully adapt to the complex working environment of cotton picking，according to the operation requirements of cotton picker,the power shift hydraulic walking system was designed.The rationality of power shift hydraulic walking system of cotton picker was verified by AMESim simulation software.The simulation results show that the pressure fluctuation of the designed automatic control mode power shift hydraulic walking system of cotton picker is smaller than that of the manual switching mode system,the impact of flow fluctuation is reduced by 4356%,and the acceleration time of vehicle speed is reduced by 4774%;after shifting,the pressure and flow are fast and stable,and there is no obvious shift impact when shifting in operation and transportation mode,which can meet the operation requirements of cotton picker.