The nonlinear dynamics of a space flexible structure presented a challenging modeling and control problem with its lumped actuator dynamics coupled with distributed link dynamics.In this paper, a two-link space flexible structure consisting of a flexible bar and a flexible beam was proposed.The bending-torsional-coupled vibration of the two-link flexible structure system was investigated.The closed-form dynamic equations of the system were derived combining Lagranges equations and the assumed mode method.Two kinds of piezoelectric actuators were used to suppress the vibration of the structure.The first was a piezoelectric torsional actuator bonded onto the root of the flexible bar.