Noncircular turning is necessary for machining various irregular shaped workpieces. Tool positioning control is essential for a noncircular turning system. This paper proposes a method of accurate tool positioning based on piezoelectric ceramics micro-displacement actuator. A Duhem hysteresis model of piezoelectric actuator has been developed, together with a control model of accurate positioning system. By using Simulink/Matlab, the control system was simulated, and then tested on a test-bench. The results show that the positioning time of control system is 0.1 seconds and the error rate of positioning accuracy is less than 5%, which can meet the accuracy positioning requirements of the noncircular turning system.