Abstract: Objective: To study the antibacterial activity and evaluate the clinical efficacy and safety of gatifloxacin. Methods: A randomized controlled clinical trial on efficacy and bactericidal activity of gatifloxacin was used in the Respiratory tract infections and Urinary tract infections. Results: （1） There was no statistical significant difference in clinical efficacy between gatifloxacin group（89.3%） and Levofloxacin （96.4%）, P =0.6110.There were no serious adverse drug reactions.（2） The results showed that the strains isolated rate, β-lactamase produced rate and the bacterial clearance rate of the two groups were 85.94% and 90.63%, 76.47% and 76.78%, 89.3% and 96.4% no statistical significance （P ＞0.05）.（3）The antibacterial activity in vitro of gatifloxacin against gram positive strains was better than evofloxacin.Gatifloxacin and evofloxacin had almost similar antibacterial activity against Enterobacter bacteria. Conclusion: The antibacterial spectrum and clinical efficacy of gatifloxacin was similar to levofloxacin and the antibiotic activity against gram positive strains was better than levofloxacin.