The cut tobacco expanding system composed of a conditioner and a dryer has the disadvantages of its complicated structure and control system, and high energy consumption; the expanded tobacco tends to be overdried and presents different physical-chemical properties, which affects the sensory quality of cigarette. Therefore, a pressurized device for pre-expanding cut tobacco was designed, which was mainly composed of a hood for feeding, pressurized airlock and steam supplying system. Steam was sprayed into the body of airlock to create a pressurized condition within the airlock, to complete the tobacco expansion process along with humidifying in a short time. The results of application showed that: the designed device could be an alternative to the traditional conditioner or to the airlock feeding device in a pneumatic drying system, which simplified the process of cut tobacco drying and expanding, occupied less site area and consumed less energy. The over-drying of cut tobacco was avoided, the duration of heating and humidifying decreased from 1 minute to 2-3 seconds, the expansion effect and intrinsic quality of cut tobacco were also improved.