Abstract: In order to overcome the disadvantages of conventional PD control with fixed gravity compensation,to improve the displacement control precision of manipulator actuated by pneumatic muscle actuator(PMA),and to increase the adaptability and robustness of the control system,a fuzzy immune PD control algorithm with fixed gravity compensation is presented by using the adjusting effect of feedback response of biological immune systems and the characteristics of fuzzy reasoning logic for approaching non-linear functions,which combines both fuzzy control algorithm and immune feedback mechanism with the conventional PD control algorithm with fixed gravity compensation.Then the algorithm is applied to fixed displacement control for manipulator actuted by PMA.The experiment results show that the algorithm is better than the conventional PD control,and is of practical value.