The utility model relates to a fire the burning furnace field, specifically be an external burning furnace that fires, including feed bracket and combustion chamber, be provided with helical tube below the hopper, be provided with the screw axis among the helical tube, combustible material passes through the screw axis and burns in carrying the rotary drum, sets up the fan air supply simultaneously, improves the homogeneity and the combustion efficiency of pay -off, the beneficial effect of the utility model: originally, fire burning furnace reasonable in design, simple structure, the cost is controllable, before living beings get into the furnace body, increased spiral stirring process, ensure that biomass feedstock is fully dispersed, increased with the area of contact of air, when the burning more abundant, improved combustion efficiency, be provided with a plurality of apertures on firing burning furnace inner tube wall, play the combustion -supporting effect of secondary.