Abstract: In order to investigate the dynamic ventilation characteristics of cigarette at different puff profiles, the pressure drop and total ventilation rate of an unlit 3R4F cigarette were measured at different puff profiles, a three dimensional mathematical model for air flowing in a cigarette was established. The model was validated via measuring the pressure drop and total ventilation rate of 3R4F cigarette during smoking at a constant velocity of 17.5 mL/s. It was found that the relative errors of both measured values and simulated values were less than 1.5%. The three dimensional and axial distributions of pressure drop and flow rate in 3R4F cigarette at either a constant draw velocity or ISO puff profile were analyzed by the established model. The results showed that at a constant draw velocity, the velocity of air entering into 3R4F cigarette was in positive proportion to its distance to the mouth end; under ISO puffing mode, the pressure drop of 3R4F was in positive proportion to puffing flow rate, while the total ventilation rate of cigarette had nothing to do with puffing flow rate and remained constant.