Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in the soil environment, and considered to be hazardous due to their toxic and carcinogenic properties. Intermediates accumulation during PAHs degradation significantly alters the overall biodegradation rate and toxicity of the soil environment. The biodegradation pathway of phenanthrene, a 3-ring PAH, consisting of 14 enzymatic steps was analyzed to determine the release pattern of the intermediates by mathematical calculation of permeability using a membrane transport model. The intermediates with high permeability such as 1-hydroxy-2-naphthoic acid were consistent with the compounds frequently observed in laboratory or field in the literature.