An optical control servo system for micro displacement was proposed based on the photodeformation effect of PLZT(Lead Lanthanum Zirconate Titanate) ceramic and its closed-loop servo control characteristic was researched via an experiment method. The control equations of servo system were derived based on the mathematical model of PLZT with coupled multi-physics fields. Then, parameters in photodeformation expression of PLZT ceramic during light on/off phases were identified through the static experiment. An experimental platform for closed-loop servo control of photo-induced micro displacement of PLZT ceramic was set up and corresponding control experiments were carried out based on on-off control strategy under different light intensities. The experimental results show that the output displacement of PLZT ceramic is controlled with simple on-off method by applying ultraviolet light. After the output displacement curve of PLZT ceramic actuator reaches the target value, some different degrees of overshoot are presented, and the output displacement of PLZT ceramic actuator fluctuates around the target value. The response speed, overshoot and fluctuation height increase with the increasing light intensity. The time of the output displacement of PLZT ceramic reaching the target value under the illumination of 400 mW/cm2 is only about 20 percent of that under the illuminated of 100 mW/cm2 by the UV light. The results lay foundation for application of the PLZT ceramic in micro actuator engineering.