Abstract: A bacterial strain Z1 capable of efficiently degrading aniline was isolated and it was seen as single carbon source and nitrogen source, from activated sludge of a urban sewage treatment plant's aeration tank. According to 16S rDNA gene sequence, preliminary identification was made. The results showed that the strain Z1was Pseudomonas sp. The optimal growth and degradation conditions of Z1 were 30℃, pH 7.0 and salinity 0.1%—1.5%. Z1 was able to almost degrade 400 mg/L aniline within 16 h. When the aniline initial concentration was 1 300 mg/L, the maximum degradation rate of aniline was 41.4 mg/(L·h) and degradation rate was 98.3% within 32 h. Strain Z1 can grow in the medium containing aniline at the concentration up to 1 800 mg/L. When aniline and phenol were seen as complex pollutants, the effect of aniline degradation decreased with the increase of phenol concentration by strain Z1. When phenol was above 370 mg/L, aniline was not degraded almost. Adding ammonium chloride could solve the degradation problem. About 43% aniline-derived nitrogen was released as ammonia in the process of aniline degradation.