In order to ensure the high precision and accurate position of manipulators, it is necessary to suppress the undesired vibration based on the active vibration control technology. In this paper, taking the elastic beam system composed of the variable mass component as the subject of study, the vibration characteristics and the active vibration control of the variable mass elastic structure are studied. The governing equations of variable massflexible beam composite structures with piezoelectric patches are derived by the modal superposition method. The vibration characteristics and the motion law of variable mass elastic beam system are obtained by simulation. A feedback controller is designed for the active vibration control of the massincrease system and the massreduction system. The time frequency analysis technology is applied to analyze the control results. The simulation results show that the quality of the change causes an additional damping as well as the change of the vibration frequency of the system. The vibration of the structure can be effectively suppressed by the feedback control in the range of the resonant frequency of the variable mass timevarying system.