A well type gas carburizing furnace is composed of a furnace body (composite furnace lining), electric heating elements, muffle cans, suspended guide tubes, hot air circulation fans (water-cooled sealed motors), furnace base, furnace cover, furnace cover lifting mechanism, carbon potential/temperature (microcomputer) control system, atmosphere system, etc. The large well type gas carburizing furnace adopts a suspended bottomless muffle (sand seal/oil seal) structure