Taking drinking water of Hohhot City as the research object, a risk evaluation on the hazard factor of nitrite in water was made from four aspects such as hazard identification, hazard description, exposure assessment and risk description. The evaluation results show that the risk quotient (QH) of nitrite in water is 40％, which indicates that the possibility that human’s intaking nitrite by drinking water causes risk to human health is little. In the meantime, taking pure Kunming mice as experimental animals, a nitrite sub acute toxicological test was made to determine the serum biochemical index. The results show that there are significant differences in the lactate dehydrogenase(LDH), aspartate amino transferase (AST), alanine aminotransferase (ALT) and urea between the experimental group, which is given nitrite according to the level of dietary exposure, and the control group. The function of liver and kidney of mice in the experimental group has been affected. Ignoring the uncertainty from the experimental animal to human, nitrite in a level of the dietary exposure maybe have bad influence to the function of human’s liver and kidney.