This work investigated the degradation of Lomefloxacin (LOM) by Fenton oxidation process. The effects of four influencing factors, including initial pH value, the initial concentration of Fe2 , H2O2 and LOM, were studied and the best reaction conditions were finally obtained. Operating at pH=6.5, [H2O2]0=0.5 mM, [Fe2 ]0=0.1 mM, 89% of LOM was removed after 5-min of treatment. The results of umu test showed that genotoxicity of the reaction system decreased during Fenton treatment. This implied that Fenton process could effectively degrade LOM to form less genotoxic products. At the same time, the antibacterial activity of the reaction mixtures exhibited decreasing tendency too, which might be attributed to the decomposition of the quinolone moiety of LOM after Fenton oxidation.