Abstract: Due to the lack of knowledge of the impact of Virtual synchronous generator（VSG）control on the mechanical structure of wind turbines,the dynamic characteristics of the drive train is studied for a doubly-fed induction generator（DFIG）under VSG control.The DFIG model is developed taking into account the flexibility of the drive train,and the VSG control of the DFIG is achieved on the rotor-side converter. Considering the impulsive disturbance of the grid frequency and the continuous disturbance of the wind speed,the dynamic characteristics of the drive train are compared for a DFIG under VSG control and traditional vector control through the simulations of the established model. The influence of the key VSG control parameters on the dynamic characteristics of the drive train is analyzed on time domain and frequency domain,respectively. The results show that,when the DFIG is operating in the VSG control mode,the impulsive disturbance of the grid frequency excites an impulsive free-torsional-vibration with a large amplitude on its drive chain,and the continuous disturbances of the wind speed triggers a continuous forced-torsional-vibration with a large amplitude and a continuous free-torsional-vibration with a small amplitude on its drive train,and the key VSG control parameters have a significant influence on the free-torsional-vibration.