A two-link flexible structure system consisting of a flexible bar and a flexible beam was proposed．The coupled bending-torsional vibration of the flexible structure system was investigated．The dynamic equation of the system was established. A piezoelectric torsional actuator was bonded onto the root of a flexible bar to suppress the torsional vibration of the flexible bar, and a piezoelectric bending actuator was bonded onto the root of the flexible beam to suppress the bending vibration of flexible beam．Experimental research was performed using a sliding mode variable structure control strategy with a saturation unit and a filter．The results show that the controlled system is stable, all the bending and torsional modes are effectively suppressed and the tip vibration of the flexible beam is dramatically attenuated．