STATCOM has been widely analyzed and discussed in flexible power flow control and operation of DFIG-based wind farm integration. Analysis on its dual-loop voltage control strategy directly affects the operation characteristics of wind farm integration. First, a circuit model of STATCOM based on VSC, which is connected to power grid through coupling transformer, is built. Then, the mathematical model of dual-loop voltage control link is derived and the impact of parameter in control link on integration operation characteristics is analyzed. Finally, a model of DFIG-based wind farm integration is established, which is using the three-machine nine-bus system as the equivalent power grid. Simulation results show that the corresponding relationship between the droop coefficient and reactive power and the power quality can be improved by using STATCOM. And through different types of fault simulation, it shows that the STATCOM can compensate reactive power quickly and improve transient stability of power system effectively even if there is the most serious three-phase short circuit fault.