NOVELTY - Conversion of biomass into energy includes preheating biomass forming raw material in flue gas waste heat utilization chamber with waste flue gas; continuously discharging the thermally decomposed gas product in dry distillation and pyrolysis system to the other processing system and periodically opening solid materials that cannot be thermally decomposed by the unloading device and loading the solid materials in water sealing tank; and periodically cleaning the solid product from the liquid water sealing and unloading system.    USE - Conversion of biomass into energy (claimed).    ADVANTAGE - The method provides fuel gas with very high grade and realizes environmental protection.    DETAILED DESCRIPTION - Conversion of biomass into energy comprises:    (A) providing a device consisting of four subsystems, which are heating system comprising combustor or high-temperature flue gas inlet of heating furnace, combustion chamber or hearth, and 1-4 layers of radiation isolation plates; dry distillation and pyrolysis system comprising pyrolysis gas outlet, sensible heat utilization chamber of pyrolysis gas, material setting device, and vertical tube; preheating and flue gas separating system comprising flue channel, flue gas waste heat utilization chamber, material loading and smoke discharge hole, and unloading and sealing hole; and liquid water sealing and unloading system comprising unloading device and water sealing tank;    (B) igniting and heating the idle device;    (C) preheating the biomass forming raw material processed to a certain shape and size with pressure or processed to proper size in the flue gas waste heat utilization chamber with waste flue gas at 180-200 degrees C;    (D) unloading the preheated biomass material into the sensible heat utilization chamber of pyrolysis gas and vertical tube through the unloading and sealing hole with the preheated biomass material;    (E) continuously discharging the thermally decomposed gas product in the dry distillation and pyrolysis system to the other processing system and periodically opening the solid materials that cannot be thermally decomposed by the unloading device and loading the solid materials in the water sealing tank;    (F) periodically cleaning the solid product from the liquid water sealing and unloading system; and    (G) repeating steps (C)-(F).