Abstract: For a flexible manipulator, how to eliminate vibration caused by the structural flexibility as soon as possible is very important. In this paper, the theory and strategy of vibration control for flexible redundant manipulators are studied. The idea of active damping control is used to suppress vibration and the corresponding optimal control method is proposed. This method can enhance the damping of the manipulator system by means of optimizing the self-motion of links to input external energy, so as to damp the vibration quickly. Furthermore, the implement of this method is discussed. Finally, with this control method, simulations of the vibration control of a planar three-link manipulator with the last link flexible are carried out. The simulation results demonstrate its feasibility.