Abstract: Intermediate frequency induction furnace has normally a thin lining. A new circuit topology of intermediate frequency power supply for induction heating is proposed. The thickness of induction furnace lining reaches 1/4 of furnace diameter in such a power supply, a double layer lining structure with 110mm masonry magnesia brick inner lining and 90mm rammed silica sand outer lining was tested. Intermediate frequency induction furnaces with thick linings possess outstanding advantages in large capacity melting, smelting, induction heat treatment, and other heating applications.