Vibrations on grinding machines are primarily caused by the unbalance in the grinding wheel. A new type of liquid-transfer active balancing device is proposed to adjust the balancing state of grinding wheel and increase grinding accuracy. In the balancing system, compressed air is used for driving balancing liquid to transfer between two opposite chambers. The distribution of liquid in balancing disk is changed and the grinding wheel is balanced. Balancing performance of the device is analysed .The experiment result demonstrates that the unbalance response is reduced from 10.2um to 0.37um at 5500 r/min and the decrease in amplitude is more than 95%.