Although the virtual synchronous generator provides a grid-friendly operational mode for power converters, it may also introduce disadvantages similar with a traditioanl synchronous generator such as power oscillation in the parallel mode due to a large virtual inertia. This paper proposes an additional damping strategy to suppress the power oscillation. After analyzing the relationship between the output power and the angular acceleration, a damping strategy is designed by the acceleration control with a disturbance compensation. Small-signal analysis is also used to study the stablity of the proposed method. Finally, experiments are carried out to verify the proposed auxiliary damping method.