According to the output performance of inchworm-type piezoelectric actuator,a novel close-loop control method based on the subsection experiential equation between actuating voltage and corresponding stepping motion displacement was proposed.Via the method,the control system could search for the optimal actuating voltage step by step so as to approach to the target position.A experiment on the closed-loop system of the inchworm-type piezoelectric rotary actuator was carried on.The experimental results show that the novel method can control the actuator for precision positioning in closed-loop mode,and the positioning error of the actuator system in close-loop mode is 0.18 μrad,which is improved by 14.4% as compared to that of the open-loop working mode.The control method has the advantages of high accuracy,quick response and so on.