A pure AMT pneumatic automatic transmission actuator is designed, and the t heoretical thermodynamic model of the shifting cylinder is set up by using the gas thermod ynamics and kinetics. Based on changing characteristics of shift indicators in v ehicle, the Simulink simulation is designed. Through testing different shift cylinde r size impacting on the rate of change of chamber pressure and set up time of chamb er pressure, clear shift cylinder optimization design objectives are established. Finally, through a balanced optimization of orthogonal test method, optimal design of AMT implemen tation pneumatic c ylinder transmission system is achieved. 