The properties of hydraulic driving are good speed-load characteristics, anti-forward rushing and accurate positioning at any location. While the properties of pneumatic driving are clean, efficient, fast. All the advantages of hydraulic and pneumatic driving can be combined in Pneumatic-hydraulic intensifier. So it is widely used in varies fields. Its very important to control the position of Pneumatic-hydraulic intensifier. In this paper, a Fuzzy self-tuning PID controller was designed and simulation experiment was done. Simulation results show that the controller performs well.