Abstract: An MRF(magneto-rheological fluid) based vibration control damper is developed for semi-active vibration control of flexible robot joints.Utilizing the properties of the magneto-rheological fluid that changes state from fluid to solid quickly,continuously and reversibly in magnetic field,a vibration control damper capable of providing a continuously variable damping force is designed.The dynamics model is developed and the performance is analyzed,and then the damper is applied to the anti-chemical mobile robot.The vibration model of shoulder joint of manipulator is developed and vibration attenuation is simulated.The prototype is developed and the vibration control experiment is done in the end.The validity of the method presented is verified by the results.