The utility model discloses a humidifying device of a cut tobacco baking machine, which belongs to the cigarette device technical field. A humidifying device is arranged in the cut tobacco baking machine, the humidifying device is composed of a steam nozzle, a steam separator and a steam source; the steam nozzle is arranged in a main hot blast pipe communicated with a drying cylinder, and the steam separator is arranged between the steam nozzle and the steam source. The steam separator is connected with a gas-open-typed film valve for controlling the spraying of the steam nozzle, and the gas-open-typed film valve is also connected with a gas-close-typed film valve. The gas-open-typed film valve and the gas-close-typed film valve are connected with an identical air compressor. A water draining valve and a manual stopping valve are connected at the lower end of the steam separator. A pressure reducing valve and the manual stopping valve are arranged between the steam source and the steam separator. The humidifying device has the advantages that the design is rational, the structure is simple, the humidifying device is easy to be implemented, the operation is simple, after the humidifying device is operated, the over-dried amount of the cut tobacco baking machine is effectively reduced, each batch of the over-dried amount is not more than 0.6 percents, and the quality of products quality is stabilized.