The utility model discloses a humidifying system of a bulk curing barn. The humidifying system comprises a heating chamber and a baking chamber, wherein an upper ventilation tunnel and a lower ventilation tunnel are correspondingly arranged on the upper end and the lower end of a wall between the heating chamber and the baking chamber, the heating chamber is communicated with the baking chamber through the upper ventilation tunnel and the lower ventilation tunnel, a heating furnace is arranged in the heating chamber, a fan is arranged on the upper part of the heating furnace, the fan is connected to the upper ventilation tunnel through an exhaust port of the fan, a cold air door for controlling the airflow to enter is arranged on the sidewall of the heating chamber, a humidity discharging channel provided with an air vent is arranged on the bottom of the baking chamber, a humidity discharging window is arranged on the tail end of the humidity discharging channel outside the baking chamber, the humidifying system is characterized by further comprising an automatic control humidifying system and an automatic control humidity discharging system. According to a humidifying system of a precise curing barn and the humidifying system of the bulk curing barn, precise requirements of a tobacco baking process on humidity can be satisfied, and the humidifying system has the advantages of good baking effect and convenience for operation.