Abstract: The distribution and variability of pore space within the tobacco segment of heated tobacco products (HTP) are important factors affecting user experience and the design of heated tobacco devices. In this study, computerized tomography (CT) combined with 3D reconstruction technology was utilized to examine the pore distribution and structural changes in the tobacco segments of HTP. The research specifically analyzed volumetric porosity, cross-sectional porosity, and annular cylindrical porosity.The results revealed that the porosity distribution was significantly inhomogeneous across different HTP samples and within individual samples along various directions, both before and after appliance insertion. The mechanical insertion of the heated tobacco device induces a redistribution and compression of the pore structure, reducing the overall volumetric porosity to 0.47. In the radial direction, the outermost annular porosity is most significantly affected by the inner wall of the eated tobacco device, showing a reduction of 28.81%, while the central area shows smaller changes. In the axial direction, the structure forms three distinct regions: a composite extruded layer, an intermediate extruded layer, and an upper extruded layer. The degree of pore extrusion increases progressively within each of these layers. Furthermore, simulations and experiments confirme that internal the airflow characteristics of HTP airflow follow an inverse relationship with the axial cross-sectional porosity distribution and volumetric porosity. The study indicates that draw resistance characteristics are influenced not only by volumetric porosity but also by the insertion mode of the heated tobacco device. These insights provide a theoretical basis and technical support for the optimal design of both HTP and the THD.