The invention relates to a reactive power compensation device capacitance measuring device which comprises a control module, a measuring module, an inversion power supply module, a liquid crystal display module and a data printing module. The control module is connected with the measuring module, the inversion power supply module, the liquid crystal display module and the data printing module. The device uses microcomputer control, and uses a real-time high-speed sampling technology and a modern power electronic technology. Without removing a capacitor group lead, the capacitance of a capacitor group can be quickly and accurately measured. The device is provided with a built-in rechargeable power supply, and has the advantages of high measurement accuracy and good reproducibility. The device uses an integrated structure, and has the advantages of light weight and being portable.