Abstract: In order to minimize the fluctuation of moisture content in cut tobacco due to the lower relative humidity in dry seasons in a non-air-conditioned primary processing department, a micro-fog air humidifying system was designed on the basis of the existing fresh air supplying system in the primary processing department. The said control system was arranged at the inlet of fresh air and the amount of water addition was controlled by the humidity sensor at the operational site to maintain desired environmental humidity and stabilize the moisture content in cut tobacco. The micro-fog air humidifying system was tested on the cigarettes of brand "Septwolves" in Longyan Tobacco Industrial Limited Corporation. The results showed that the inter-batch stability of relative humidity in the non-air-conditioned primary processing department in dry seasons increased by 56.3%, and the inter-batch consistencies of moisture contents in dried, stem-blended and flavored cut tobacco raised by 19.0%, 12.9% and 30.8% respectively. This technology provides a support for improving the processing quality of cut tobacco.