The core principle of induction forging furnace is to convert power frequency 50HZ AC to medium frequency (300HZ-20khz). The three-phase alternating current is rectified into direct current, Then the direct current is changed into adjustable intermediate frequency current through a frequency conversion device, the intermediate frequency alternating current that flows through the capacitor and induction coil, creating dense magnetic field lines in the induction coil, and cut the metal material which is placed in the induction coil, creating a large eddy current in the metal material, which also has some properties of intermediate frequency current. That is the heat generated by the flow of the metal's own free electrons through a resistive metal body.