The utility model discloses a flue fire damper. The device comprises a flue gas channel formed by a shell, one end of the smoke channel is provided with an air inlet; the other opposite end is an airoutlet end; the air outlet end is provided with an end face matched with the smoke channel. Wherein an air outlet is formed in the end face, a rotatable valve plate which corresponds to the air outletand can only be opened towards the air outlet direction is arranged on the end face, and a high-temperature closing device which can enable the valve plate to be forcibly closed towards the air inletside at a set temperature and is provided with a locking mechanism is arranged on the end face, so that the valve plate is always in a closed state. The utility model has the advantages that the opening is flexible, the high-temperature closing device is simple in structure and good in oil smoke discharging effect, when the temperature of smoke in the public smoke flue is in a very high emergencystate and reaches the set warning temperature, the valve plate in the open state is forcibly closed through the high-temperature closing device, the valve plate of the fireproof valve is always in alocked closed state, and therefore the life safety of residents is protected.