Abstract: Predicting the morphological evolution of porous media under coupled thermo-fluid-solid-chemical processes remains a common challenge in aerospace, energy, chemical engineering, and many other fields. In this study, a hybrid micro-continuum-scale numerical method is proposed. Taking the oxidation ablation of a three-dimensional carbon fiber porous material exposed to a high-temperature oxygen flow as an example, a structured grid is employed to achieve coupled simulations of fluid flow, heat transfer, chemical reactions, and dynamic morphology evolution. The result indicate that porosity determines the ablation mode of the material. For low-porosity structures, ablation is dominated by surface oxidation recession, whereas high-porosity structures also experience volumetric ablation due to deeper oxygen penetration. Quantitative analysis reveals a positive correlation between the porosity and the mass loss rate of carbon fiber porous materials. After 20 s of ablation, the mass loss rates for materials with porosities of 0.92 and 0.88 reach as high as 100% and 99.3%, respectively; in contrast, when ε = 0.85, the mass loss rate decreases significantly to approximately 74.5%. Furthermore, constrained by the diffusion limit caused by an insufficient oxygen supply, the ablation recession rate at 3000 K exhibits a nonlinear behavior over time, increasing initially and then decreasing. The proposed method is capable of accurately capturing the dynamic evolution of ablation morphology in three-dimensional space and at the pore scale, providing an effective numerical tool for evaluating the ablation resistance of porous media under extreme environments.