The cover type furnace is composed of a heating cover, two furnaces, two inner covers and a cooling cover. The heating cover is made of steel plate and welded tightly. The lining of the furnace is a full-fiber module structure with energy-saving new technology. The furnace base is insulated water cooled vacuum rubber seal structure, stainless steel air guide pedestal, high power vacuum seal fan. The inner cover is made of stainless steel plate, and the bottom flange and vacuum sealing groove are made of large vertical lathe. The cooling cover is rapidly cooled by spiral air supply from double fans. The vacuum pump is 2x series rotary vane mechanical vacuum pump. The furnace temperature control cabinet uses microcomputer program process curve to control temperature with high precision, and automatically completes the heat treatment process curve. The thyristor is directly controlled by microcomputer through calculation to adjust the power in the furnace, reduce the fluctuation of the power grid, and automatically change the power according to the amount of furnace loading and the slope of the process, so as to achieve high power saving and temperature control.