Nitrobenzene is an important chemical raw material. Owing to human activities of production and living, it may become the pollution source of the water and the environment. In order to understand the possible toxicity of nitrobenzene to aquatic animals, the DNA damage of the nitrobenzene was studied at different concentrations to the liver and pancreas, kidney, fin, sperm cell of zebrafish by singlecell gel electrophoresis technique. When the treatment dose of nitrobenzene was at the national standard for surface water environmental quality（GB3838-2002, 0.017 mg/L）, the DNA damage of the liver and pancreas, kidney and sperm cell was not obvious, being 30%, 33% and 44% respectively. The results were no significant difference compared with the control group（P>0.05）. In the same concentration, the DNA damage rate was as high as 69% for epidermal cells of fins. When the concentration of nitrobenzene was higher than the national standard, it caused the serious DNA damage to the liver and pancreas, kidney and sperm cell. When the concentration of nitrobenzene was 0.106, the damage rates were 48%，62%，61%，82%；at 0.213 mg/L those were 42%，87%，76%，56%； those were 52%，87%，75%，75% at 0.425 mg/L； those were 58%，95%，93%，85% at 0.850 mg/L； those were 62%，90%，99%，83% at 1.700 mg/L respectively. All the treatments concentration above the national standard were significant differences compared with the control group（P<0.05）. The result showed that the nitrobenzene had no obvious toxicity to the somatic cells and the sperm cells of the zebrafish when the concentration of nitrobenzene in the water environment was lower than the national standard. When the concentration of nitrobenzene was higher than the national standard, the nitrobenzene had stronger toxic effect on the somatic cells and the sperm cells of the zebrafish, and the DNA damage rate rose with the nitrobenzene dose increasing, and it presented the specific dose of the damage effect. So the concentration of nitrobenzene in fishery water standard should not be higher than the national standard.