NOVELTY - Reactor for composting device comprises a fermenting system and a gas collecting processing system. The fermenting system includes a rectangular fermenting pond (3) and a tapered gas collecting pond (8), where bottom part of the fermenting pond has orderly arranged padding layer (7) and a stainless steel screen (4), the middle part has uniformly arranged gas guide pipes (1) having holes, and bottom ends of the gas guide pipes pass through the padding layer to be fixed on the stainless steel screen, and the gas collecting processing system includes a gas collecting pond and a gas processing system.    USE - The reactor is useful for composting device.    ADVANTAGE - The device: is simple and maintains the temperature of the piled body when composting in an aerobic manner; maintains low external temperature when composting; is suitable for continuous production; is good for collecting the odor when composting, and also collects and utilizes ammonia produced during composting.    DETAILED DESCRIPTION - Reactor composting device comprises a fermenting system and a gas collecting processing system. The fermenting system includes a rectangular fermenting pond (3) and a tapered gas collecting pond (8), where the bottom part of the fermenting pond is orderly provided with a padding layer (7) and a stainless steel screen (4), the middle part is uniformly provided with gas guide pipes (1) having holes, and the bottom ends of the gas guide pipes pass through the padding layer to be fixed on the stainless steel screen (4). The gas collecting processing system includes a gas collecting pond and a gas processing system, where the gas collecting pond is placed below the fermenting pond and is closely connected to the fermenting tank. The gas processing system comprises an aspirator pump and an ammonia absorbing tank, where the bottom part of the gas collecting pond is connected to the aspirator pump which is connected to the ammonia absorbing tank.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the reactor composting device.    Gas guide pipes (1)    Fermenting pond (3)    Stainless steel screen (4)    Padding layer (7)    Gas collecting pond (8)