Flue non-return device

The utility model discloses a flue non-return device. The flue non-return device comprises a guide cylinder and a flue gas non-return assembly, a check valve cover is hinged to the end opening of theflow guide cylinder and can open the end opening of the flow guide cylinder when airflow impacts the check valve cover. Indoor smoke can be discharged into the building public flue, the guide cylinderis in a normally closed state when no smoke exists, and smoke in the building public flue can be prevented from entering kitchens and baths; when a kitchen and a bathroom are on fire, the check valvecan close the smoke channel in time, and poisonous hot smoke is prevented from flowing in series and diffusing along the public flue. When the public flue gas duct is on fire, the check valve cover on the guide cylinder can also automatically seal the port of the guide cylinder, so that flue gas in the public flue gas duct is prevented from flowing back into kitchens and baths; and the practicalvalue and the popularization