Abstract: This experiment is to study the effect of norfloxacin lactate on sperm shape abnormality，subchronic toxicity，accumulative toxicity and tolerance in Kunming mice. Healthy Kunming mice were chosen for experiment that adopted intragastric administration. Sperm shape abnormality，the organ coefficient，the accumulation coefficient and tolerance of rats were observed and calculated. In the sperm shape abnormality test, the positive control group of sperm shape abnormality has significant higher than the high dose, middle dose, low dose and the blank control group. After 60 d, the difference of weight changes of body between female rats in high dose group and control group was obvious; the organ coefficient of lung in high dose group of female mice were lower obviously than the control group and the low dose group. The organ coeffcient of lung and kidney in high dose group of male mice were lower obviously than the control group; no rats was dead through the cumulative toxicity test and accumulation coefficient was larger than 5; in the tolerance test，the mortality of rats in the test group was significantly lower than in the control group. It was shown from the experimental results that norfloxacin lactate was light cumulative toxicity and the sperm shape abnormality test was negative. But if rats were intragastrical with norfloxacin lactate for a long time，it might have an influence on lung and kidney of rats and norfloxacin lactate would induce a certain obvious tolerance.

Key words: norfloxacin lactate; sperm shape abnormality test; subchronic toxicity; acumulative toxicity; tolerance