Abstract: In order to investigate the factors affecting the moisture content in cigarettes packed in packets during storage, the influences of pumping method and aeration method on the test results of pack tightness were compared, and a calculation model for the moisture content in cut filler was established based on the variation of packet weight. The influences of storage time, storage temperature, relative humidity and packet tightness on the moisture content in cut filler of packed cigarettes were studied. The results showed that: 1) The test results of the pumping method and the aeration method could characterize the sealing property of cigarette packets and their determination coefficient was 0.887 3. The tightness of different packets in 300 samples fluctuated greatly with the coefficient of variation of 68.78%. 2) After storing for 15 days in an environment with temperature at 40 ℃ and relative humidity at 82.32%, the moisture content in the cut filler significantly increased with the decrease of the tightness, and their relationship was consistent with a power function model with a dermination coefficient of 0.977 9. The external moisture entered into the packet mainly through the micropore and the seam of packet film, and the theoretical critical value of tightness was 0.73 kPa. 3) During storage, the variation rate of moisture content in cut filler increased with the rise of ambient temperature. The critical relative humidity for cigarette packets was 60.13%, when the relative humidity of the environment was lower than that, the moisture in cut filler would be desorbed; while the moisture would be absorbed when the relative humidity was higher than that.