Abstract: To achieve non-destructive detection of the airtightness of cigarette packets and improve the quality of cigarette packaging, a non-destructive detection method based on apparent leakage area was developed. The impact of packet airtightness on moisture migration inside and outside the packet was investigated, and the optimal process parameters were determined through single factor and response surface experiments. Using conventional cigarette packets packed with Biaxially Oriented Polypropylene (BOPP) film with a thickness of (20.0 ± 1.0) μm as the research objects, the results showed that: 1) The pressure drop curves of the standard articles with different leakage areas in the closed system conformed to an exponential function model. A standard curve for apparent leakage area was established based on the correlation between the characteristic parameter t₁ in the model and the area of the leakage hole. This method featured good accuracy and repeatability. 2) When the apparent leakage area of a cigarette packet was ≤4.5×10^-10 m², moisture migration primarily occurred through internal moisture exchange, suggesting that this threshold could be used as a target for controlling the airtightness of cigarette packets. 3) The optimal process parameters for the testing machine were a side iron temperature of 130 ℃, an end iron temperature of 155 ℃ and a packet film shaping device temperature of 120 ℃. Under these conditions, the average apparent leakage area of the packets was 4.08×10^-10 m². 4) After parameter optimization and U-shaped blade modification, the average apparent leakage area of cigarette packets decreased to 3.94×10^-10 m². The quality of cigarette packet packaging was significantly improved.