Abstract: The bacteria that can efficiently degrade nitrobenzene and aniline have been separated from various sources. By studing the biodegradation characteristics of these two compounds, it is found that C.perfringens can degrade nitrobenzene to aniline in anaerobic process, Pseudomonas mendocina and Klebsiella pneumonia can transform nitrobenzene to harmless substance respectively in aerobic process but the degradation rate is lower than that in anaerobic process. Nitrobenzene inhibits the degradation of aniline in aerobic condition, and the opposite effect is not obvious so that the degradation rate of mixed bacteria to mixed substances will decrease. The degradation mechanisms of different microbes for the wastewater containing nitrobenzene and aniline show sharp differences. The efficient microbes can degrade not only the initial pollutants but also the next products to harmless substances entirely.