In the study, instead of using expensive servo valves, three inexpensive high-speed solenoid valves were adopted and a fuzzy PWM controller was designed to control the linear and rotational positions of a pneumatic robot cylinder. The modified differential PWM method is proposed to eliminate the dead zone and to improve the nonlinear characteristics between the pressure difference of the cylinder and the duty ratio of the PWM control signal. The experimental results have shown that the servo pneumatic system with the proposed fuzzy PWM controller exhibits good performance.