The Intermediate frequency furnace is a power supply device that converts power frequency 50HZ alternating current into intermediate frequency (300HZ and above to 1000HZ), converts three-phase power frequency alternating current into direct current after rectification, and then converts direct current into adjustable intermediate frequency current, which is supplied by capacitors. The intermediate frequency alternating current flowing in the induction coil generates high-density magnetic lines of force in the induction coil, and cuts the metal material contained in the induction coil, generating a large eddy current in the metal material.