Abstract: Two Flavobacterium FCN1,FCN2,and a Brevibacterium BCN1 were isolated from the sludge contaminated by coke-plant water for a long time.Before isolation,the sludge was cultivated by naphthalene as sole carbon source for 7 weeks.The degradation tests of phenanthrene and pyrene by our isolates were carried out under still-reaction-bottle-aeration and shaking-aeration conditions.The co-metabolic characteristics of several co-substrates and inorganic ions on the biodegradation of phenanthrene and pyrene by our isolates were also studied.The results show that phenanthrene and pyrene can be degraded by the three isolates effectively,the BCN1 is the most effective and that such degradation process can be accelerated by rinsing-rice-water.The phenol,urea and glucose play inhibiting actions on the degradation of phenanthrene under the existence of FCN1 and FCN2.All co-substrates used have promoting effects on the degradation of phenanthrene by BCN1.The ferric ion can decrease the promoting effect of the rinsing-rice-water in our two Flavobacterium reaction systems,but can increase that of the rinsing-rice-water in the BNC1 reaction system.