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 (THD). In this study, Computerized Tomography (CT) combined with 3D reconstruction technology was utilized to examine the pore distribution and structural changes in heated HTP tobacco segments. The research specifically analyzed volumetric porosity, cross-sectional porosity, and annular cylindrical porosity.The results revealed that the porosity distribution was significantly inhomogeneous between different HTP samples and within individual samples in various directions, both before and after appliance insertion. The mechanical insertion of the THD 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 THD, 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 in each of these layers. Furthermore, simulations and experiments confirmed that the airflow characteristics of the internal HTP airflow follow an inverse relationship with the axial surface 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 THD. These insights provide a theoretical basis and technical support for the optimal design of both the HTP and the THD.