The invention discloses a reactive power compensation device control method for preventing large-scale chain offline of wind generation sets and belongs to the technical field of wind power generation. The reactive power compensation device control method comprises the following steps: a low-voltage running limit of reactive power compensation devices is set and when the voltage of a grid connection point is lower than the low-voltage running limit, that a power grid fault occurs is judged, and a grid connection switch is automatically disconnected; after the fault is removed, input commands are issued to part of the reactive power compensation devices by a system control center according to the network operation state to ensure that the voltage rapidly returns to the standard value. Through the adoption of the method, the fault of a wind power system can be effectively prevented from being expanded and the chain faults are prevented.