The invention relates to the field of power equipment, in particular to a reactive power compensation control device comprising a radio frequency module, an antenna, an MCU controller, a three-phase voltage collecting circuit, two sets of three-phase current collecting circuits, a capacitor switching circuit, an alarm output circuit and a temperature control circuit, wherein the MCU controller isrespectively connected to the three-phase voltage collecting circuit, the three-phase current collecting circuits, the capacitor switching circuit, the alarm output circuit and the temperature controlcircuit. A capacitor switching method sets the capacity of the capacitor and an over-temperature protection value of the capacitor. The MCU controller controls the corresponding capacitor to be put into operation, and cuts off the capacitor loop and outputs an alarm when the temperature of the capacitor exceeds the set upper limit. The reactive power compensation controller and the capacitor switching method obtained by the invention have the function of wireless temperature measurement and capacitance detection of the capacitor.