The invention relates to a reactive power control system applicable to wind farm grid-connection point voltage control and a reactive power control method applicable to the wind farm grid-connection point voltage control. The system includes a scheduling system; the scheduling system is connected wind a wind farm AVC system; the wind farm AVC system is connected with a wind farm concentrated SVC, a measuring device and a fan SCADA system respectively; and the fan SCADA system is connected with fans in a wind farm. The control method comprises the following steps that: the sequence of reactive power output adjustment performed on the fans by an AVC system is determined according to the sensitivity of wind farm grid-connection point voltage; and the total number of reactive power controllable fans is determined according to whether the reactive power of each fan is controllable or not, such that the upper and lower limits of adjustable reactive power total quantity of the fans can be determined; and reactive power total quantity Qreg of the wind farm, which is required to be adjusted, can be determined, and the Qreg is distributed according to a fan-first and SVC-second reactive power distribution strategy. With the reactive power control system and method applicable to the wind farm grid-connection point voltage control of the invention, the defect of long control cycle of the AVC system in the wind farm can be eliminated, and fast response adjustment ability of the SVC can be given to full play.