A new hydro-vibration method based on the swing of a variable inertia flywheel is proposed to enhance the efficiency added by the damping effect of the hydro-valve. The vibrator is connected to the actuator through its piston rod, and the hydro-motor is connected to the flywheel through its shaft. Thanks to a hydraulic transmission circuit consisting of the actuator and hydro-motor the motor with the flywheel is driven to swing when the actuator pumps alternating pressure oil with the vibration. Thus, the rotational inertia of the flywheel changes with the motion phase of the vibrator, and the vibration intensifies with the momentum cycling in the system. This method helps save energy without throttling loss which often exits in hydro-valve based method. Theoretical analysis and Matlab simulation show that the vibration effect is related to structural parameters such as working area of the actuator, displacement of the hydro-motor and adjustment coefficient of the flywheel.