Pneumatic driven system has been widely used in industrial automation mainly for relatively simply tasks with open-loop control. With regard to closed-loop controlled axes in robotics, servo-electric driven systems have been dominant up to now. This paper introduces a new closed-loop control servo-pneumatic system that can do continuous positioning. The mathematical model of the servo-pneumatic system was developed accurately through analysis of the flow characteristics of the proportional flow valve and the friction of the cylinder. The optimum control strategy with friction compensation is presented in this paper. Experiments demonstrate that the servo-pneumatic system has excellent tracking characteristics and can rival the expensive servo-electric system in many areas of industrial control. Pneumatic driven system has been widely used in industrial automation mainly for relatively simply tasks with open-loop control. With regard to closed-loop controlled axes in robotics, servo-electric driven systems have been dominant up to now. This paper introduces a new closed The mathematical model of the servo-pneumatic system was developed accurately through analysis of the flow characteristics of the proportional flow valve and the friction of the cylinder. The optimum control strategy with friction compensation is presented in this paper. Experiments demonstrate that the servo-pneumatic system has excellent tracking characteristics and can rival the expensive servo-electric system in many areas of industrial control.