Dry type iron core series reactor is an important supporting equipment of reactive power compensation device in power system. After the power capacitor and dry-type iron core reactor are connected in series, it can effectively restrain the high-order harmonics in the power grid, limit the switching inrush current and switching overvoltage, improve the voltage waveform of the system, and improve the power factor of the power grid, which plays a great role in the safe operation of power capacitors and other power equipment.