Abstract: A scheme of parameter-adaptive command augmentation sys-tem（CAS） is designed for supersonic-jet's lateral motions. Its digital simulation is also investigated. The purpose of the work is to provide the airplane with superior handling quality against rapid variation of the aircraft's lateral parameters and affection of external disturbances.The paper deals with the behaviors of the designed CAS during constant altitude coordinated turns both at constant speed and at decreasing speed, and under stochastic side-gust disturbances as well. The time responses of the aircraft with the designed CAS are compared with those of the free aircraft under the above conditions. It is shown that the version of the adaptive CAS is superior in anti-disturbance and adapta-bility to time-varying parameters.The microcomputer implementation of the parameter-adaptive lateral CAS and the choice of the microcomputer are also considered,