This paper studies a reactive power control strategy to stabilize voltage by controlling the reactive output of each wind power field with large scale wind farm integration. Firstly, the reactive adjustment quantity of voltage control point is calculated based on the deviation of reference voltage and measured voltage and then the reactive adjustment quantities distributed to each wind farm using equal network loss increase ratio law. This strategy makes full use of the reactive regulating capacity of the var compensation equipment of each wind farm，so that they can participate in the voltage stability control in grid-connected region. Wind speed variations and voltage drop has been simulated and result show that the voltage variation could be inhibited by this strategy.