Beijerinckia fluminensis 6-1H isolated from coking wastewater environment was effective in degrading phenanthrene. The degradation path and specific activity of enzyme were analysed in order to find out biodegradation mechanism. Metabolites detection by UV-Vis, GC-MS, FTIR and concentration variation of salicylic acid and phthalic acid revealed eight important metabolites, 1-hydroxy-2-naphthoate, 1-naphthol, salicylic acid, gentianic acid, phthalic acid, maleoyl pyruvic acid, pureonebio and β-carotene , generated during phenanthrene degradation by strain 6-1H. Specific activity of enzyme analysis revealed that four kinds of enzymes involved in phenanthrene degradation contained 1-hydroxy-2-naphthoicacid hydroxylase, 1-naphthol hydroxylase, phthalic acid dioxygenase and salicylic acid-5 hydroxylase during phenanthrene degradation. Based on the metabolic data and the specific activity of enzyme analysis, here we proposed a pathway involved C3,4-dioxygenation for phenanthrene degradation by strain 6-1H, generated metabolites 1-hydroxy-2-naphthoate and 1-naphthol. Then form gentianic acid through salicylic acid, and gentianic acid continues to be degraded to maleoyl pyruvic acid until complete mineralization. Or 1-naphthol continues to be degraded to phthalic acid, finally generating β-carotene, H2O and CO2 through protocatechuic acid. This study expands our understanding of the degradation mechanism of phenanthrene degradation, which can be useful for the bioremediation applications.