Abstract: Based on the online dynamic balance device principle, the design method of the embedded double-face online dynamic device is proposed.The balance disks can be disengaged from the spindle through a hydraulic system, and the rotation speed of the disengaged disks is kept steady and under the speed of the spindle through a friction torque.The system realization of signal acquisition, signal analysis and control, and hydraulic pressure are designed.The feasibility is proved by examples.