In order to study the internal pore distribution of a cigarette and to address some of the shortcomings of the current measurement methods for cut tobacco filling state in cigarettes, three-dimensional scanning was performed by using microfocus X-ray computerized tomography (CT) imaging technology, and the obtained structural information was processed to develop both two-dimensional cross-sectional image stacks and three-dimensional reconstruction model of a cigarette. The analysis and characterization methods for the internal porosities of different cross-sections, fan-shaped segments and circular columns of cigarettes were established. The CT scanning results of unlit king-sized, demi-slim, slim cigarettes and heated tobacco rods were analyzed. The results showed that: 1) The porosities of different cross-sections indicated that the axial changes of conventional, demi-slim and slim cigarettes were basically the same, namely the porosities of the middle sections fluctuated around the average porosities, and those of both ends first decreased and then increased. However, the porosities of the middle sections of the heated tobacco product fluctuated uniformly, and those of both ends increased directly. 2) The porosities of different segments of traditional cigarettes and heated tobacco products had the same change trend, namely first decreased, then increased and then decreased. 3) Except for the marked increase in the porosity of the 2.5-3.0 mm circular columns in the conventional cigarettes, the porosities of the different circular columns of the demi-slim and slim cigarettes and the heated tobacco rods showed a similar trend, namely first increased, then decreased, and then increased.