The invention discloses a magnetic controllable parallel reactor circuit. A magnetic controllable parallel reactor circuit is in connection with a bus of an extra-high voltage power transmission system, and an AC input terminal and a DC output terminal of an excitation system are respectively in connection with the magnetic controllable parallel reactor, allowing the excitation system to receive an AC supply voltage signal from the magnetic controllable parallel reactor, and output a DC voltage signal to the magnetic controllable parallel reactor so as to change the magnetic saturation of an iron core of the magnetic controllable parallel reactor, and realizing smooth change of the capacity of the magnetic controllable parallel reactor. According to the invention, an AC power supply of the excitation system is selected from the magnetic controllable parallel reactor, and an external power supply is not needed, allowing a capacity adjusting process to be independent of the external power supply, and improving the whole reliability compared with the prior art.