Quinoline is poisonous organic compound and not easy to be biodegraded.Nineteen bacterial strains were screened out by enrichment culture to decompose quinoline as sole nitrogen source .By the quinoline-degrading test , HY9 is the best quinoline -degrading bacterium as experimental strain .The curves of deg ration and growth of quinoline -degrading show that the growth ofHY9 strain and degradation of quinoline are concurrent , optimal time is 50～ 70 hours , which is stable stage .Effects of glucose and the volume of initial quinoline on degradation of quinoline were studied.The optimal carbon source is glucose and volume fraction of quinoline is 1 .4 m L/ L.By orthogonal test determination, the optimal conditions are as following :temperature is 35 ℃ , pH is 7.0, time of culture is 4 days, 125 r/ min rotation speed of mechanical shaker .Temperature is the key factor for the growth of cell, then is rotation speed and pH , time o f culture is the unimportance factor .The initial test of denitrification indicates that the denitrification percent for diesel oil is only 13 %.Low denitrogen rate is probably because that the mixing of oil and water is no t perfect , efficient mixing of oil and water is important for the enhancement of denitrogen rate for diesel oil.