When the manipulator is lightweight, especially for space application, the robotic systems are subject to high degree of flexibility and encounter unavoidable mechanical vibration. In this paper, the experimental setup of flexible manipulator was designed and built to verify the approach proposed for actively controlling the unwanted residual vibration.The control scheme consists of one AC servomotor actuator to drive the flexible link through harmonic gear speed reduction, and piezoelectric ceramics (PZT) patch attached to the surfaces of the flexible link used as sensors. Several active vibration controllers including the modal PD, soft variable structure control (VSC) and gain select VSC method were investigated to suppress the unwanted vibration due to environmental stimulation, especially the undesirable oscillations caused by the motor torque during the hub slewing motion. The comparative experimental results showed that the vibration of the system was significantly suppressed, and the adopted control methods were effective.