Using a virtual synchronous generator (VSG) control technique to simulate the external characteristics of the synchronous generator can provide certain damping and inertia for the power system. However, wind turbine generator (WTG) based on VSG control can easily cause low-frequency oscillation of the power system. In this paper, the small-signal stability of grid-connected wind farm systems based on VSG control is studied. Firstly, a single-small signal model is developed for both single and multiple VSG control-based wind turbine and grid-connected wind farm systems. Then, the system’s eigenvalues are obtained by solving the state matrix, and the system’s oscillation modes are analyzed. Finally, the effects of varying key parameters on the small-signal stability, such as virtual inertia, virtual damping, and line connection reactance, are analyzed using the eigenvalue method.