An intelligent circular tube system is proposed. The system is compos ed of a thinwalled cantilever circular tube with an equivalent disk at its fre e end, a piezoelectric torsional actuator and a str ain gauge sensor. The torsional vibration of the system is investigated theoreti cally and experimentally. In consideration of the optimization of piezoelectric torsional actuator of the intelligent system, dynamic equations of the system are deri ved using the Lagrange equation and the assumed mode method. The statespace ex pression of the dynamic system is developed. The minimum input energy of the con troller is chosen as the actuator optimization criterion. Optimal position of th e piezoelectric torsional actuator is obtained using Genetic Algorithm. The obta ined optimal position is reasonable. An experimental system is established. When the actuator is placed to the optimal position and the strain feedback control is implemented, the torsional vibration of the tube is suppressed effectively.