A series of novel naphthyridone derivatives containing mono/difluoro-methyloxime pyrrolidine scaffolds were designed and synthesized. These derivatives were initially evaluated for their in vitro antibacterial activity and compounds 13a1, b1 were chosen for further evaluation their in vivo activity against systemic infections in mice. The results indicate that all of the target compounds have considerable in vitro antibacterial activity. In the in vivo experiments, 13b1 was found to be more effective than the parent drug gemifloxacin against the tested five strains, and especially its activity (ED(50):21.27 mg/kg) is 5.2-6.1 times more potent than gemifloxacin and ciprofloxacin against clinically important Gram-negative pathogen Pseudomonas aeruginosa.