Abstract: In order to investigate the variations in puff-by-puff releases of acidic smoke components in the mainstream cigarette smoke with different filter ventilation rates and circumferences, the releases of the acidic components were measured from cigarettes with circumferences of 17, 20 and 24 mm and the filter ventilation of 0, 25% and 50%. At the same filter ventilation rate, the puff-by-puff releases of acidic components in mainstream smoke of cigarettes with different circumferences were compared. At the same cigarette circumference, the differences in the average puff-by-puff releases per unit tar of acidic components, the trends and fluctuations of puff-by-puff releases in mainstream smoke of cigarettes with different filter ventilation rates were also investigated. The results showed that: 1) The puff-by-puff releases of acidic and conventional chemical components in mainstream smoke of cigarettes with the circumferences of 20 and 17 mm were significantly different from those of common cigarettes with the circumference of 24 mm, while the differences between the medium and slim cigarettes were small. 2) At the same filter ventilation rate, the average puff-by-puff releases of acidic components, such as butyric acid, caprylic acid, stearic acid and so on, in the slim and medium cigarette smoke were higher than those of the 24 mm circumference cigarettes. The nicotine levels in the slim and medium cigarette smoke were lower than that in the common circumference cigarettes. 3) The circumferences of unventilated cigarettes affected the puff-by-puff releases of chemical components slightly. With the increase of filter ventilation rate, the differences in puff-by-puff releases of chemical components in mainstream smoke between the common cigarettes and slim/medium cigarettes increased. 4) The first puff releases of heptanoic acid and caprylic acid were higher, which was more obvious for unventilated cigarettes. 5) For the slim and medium cigarettes, with the increase of filter ventilation rate, the average puff-by-puff releases per unit tar for small molecular organic acids, such as formic acid and acetic acid, decreased and the fluctuations of puff-by-puff releases reduced. The average puff-by-puff releases per unit tar of advanced fatty acids, such as palmitic acid and stearic acid, increased, however their reduction in puff-by-puff releases was obvious.