〔Abstract〕 Objective To compare the pharmacokinetic characteristics of antofloxacin in plasma and lung tissues of pneumonia rats and normal rats. Methods 20 Sprague Dore (SD) male rats were randomly divided into a control group and an observation group, with 10 rats in each group. Among them, the rats in the observation group were established streptococcus pneumoniae models, and were given antofloxacin by gavage. Lung tissue and blood of two groups of rats were sampled simultaneously by microdialysis technique. Drug concentrations in blood and lung tissues were determined by high performance liquid chromatography (HPLC), and the average residence time, drug elimination half-life and lung tissue penetration rate of antofloxacin were calculated. Results After administration, there were no significant differences in the average resident time and elimination half-life between lung tissue and plasma (P > 0.05). However, the average resident time and drug elimination half-life in lung tissues of rats in the control group were significantly shorter than those in the plasma, with statistical significance (P < 0.05). The average penetration rate of antofloxacin to lung tissue in the observation group was significantly higher than that in the control group, the difference was statistically significant (P < 0.05). Conclusion The concentration of free drug in lung tissue of pneumonia rats was higher than that of normal rats after ingastric administration of antofloxacin, and the penetration of the drug in lung tissue of pneumonia rats was stronger than that of normal rats, so the effective concentration of drug for removing streptococcus pneumoniae was achieved.