Abstract: To analyze the dynamic performance of pneumatic clutch actuator in automatic mechanical transmission (AMT) system, the mathematic models of single-acting cylinder and clutch actuator transmission were built on the basis of in-depth research and analysis of clutch actuator. In the established models, the transfer characteristics of force and displacement were specially considered. Further, the isentropic model was used to analyze the pneumatic actuator's characteristics. Simulation has been implemented using Matlab/Simulink. The accuracy of proposed models was proved by the real vehicle test. The results of this work might lay the foundations for designing pneumatic clutch actuator in AMT system.