Abstract: Aiming at the problem that the unclear dynamic characteristics of porosity during the drying process of Zanthoxylum schinifolium lead to insufficient basis for process optimization and structural design, this study adopts a method combining experimental analysis and numerical simulation to reveal the evolution law of porosity in Zanthoxylum schinifolium bulk from a multi-scale perspective.The results show that the porosity varies in the range of 0.345-0.591.In the initial stage(0-120 min, Mc≥34.46%), the layer thickness L changes slightly (from 0.2 mm to 0.1938 mm, a decrease of only 3.1%), and the pressure difference ΔP fluctuates slightly (432.3-513.9 Pa). In the main drying stage (120-390 min, 10.45%≤Mc≤34.46%), the porosity decreases significantly, the pressure difference ΔP drops sharply by 35.2%, and the fruit body contracts obviously. In the final stage (t>390 min, Mc≤10.45%,and the Zanthoxylum schinifolium bulk layer shows a "cracking" phenomenon locally), the layer thickness L abnormally expands by 0.018 mm. Meanwhile, an ε-Mc mathematical model is established (R²=0.9778). Combined with numerical simulation, it is shown that the heat transfer in the bulk layer starts from the bottom center and preferentially diffuses upward and inward along the wall (steady-state temperature 70.1℃). This heat diffusion path coincides with the order of "cracking" in the Zanthoxylum schinifolium bulk layer in practice. The heat transfer of a single particle is divided into three stages: the shell-breaking heat transfer stage (heat breaks through the shell to transfer heat to the seed, and the Zanthoxylum schinifolium shell undergoes slight contraction deformation); the internal heat transfer dominant stage (the Zanthoxylum schinifolium seed gradually warms up, and the contraction of the Zanthoxylum schinifolium shell gradually increases); and the heat balance approaching stage (the internal temperature of the Zanthoxylum schinifolium seed tends to stabilize, and the deformation of the Zanthoxylum schinifolium shell reaches its peak value of 0.487 mm). This study provides a theoretical basis for the optimization of the Zanthoxylum schinifolium drying process and the research on heat and mass transfer mechanisms.