Distributed generation mostly uses a power electronic converter as interface to interact with the power grid. Virtual synchronous generator (VSG) control technology has become a new scheme of inverter control because of its excellent internal and external performance in simulating a traditional synchronous generator. However, it is easy to excite the current transient process of the line inductance in fast-moving power electronic devices, and this will have adverse effects on the system. Considering the transient process of line inductance, a dynamic small signal model of system output power is established. From the model, the reason for oscillation is related to the output impedance of the system. In this paper, a new damping control strategy is adopted. By introducing virtual complex impedance into the voltage outer loop, the impedance characteristics of the system can be reshaped and the power oscillation can be suppressed. Both simulation and experiment verify the power frequency oscillation in VSG and the effectiveness of the proposed control strategy. This work is supported by the National Natural Science Foundation of China (No. 62076243).