Objective  To investigate the antibacterial effect of novel antibiotic  methanesulfonic acid gatixincin   in vitro   and   in vivo  ,comparing with the antibiotic  gatixincin which has been in clinical trial with the approval of National Drug Surveillance and Manage Bureau.Methods  According to the national pharmacodynamic experiment guideline of class Ⅱ novel antibiotic,the tube dilution method was selected for the antibacterial assay   in vitro   and KM mice were chosen for anti  infection test   in vivo  .Results  There was no significant difference between the MIC value, MBC value or KCs of methanesulfonic acid gatixincin and positive control drug  gatixincin against 232 strains (clinical bacteria and control strains).Various bacteria amount did not significantly affect the MIC values of methanesulfonic acid gatixincin and positive control drug,however,low pH value did greatly inhibit methanesulfonic acid gatixincin and positive control drug’s antibacterial activity.In the mice model infected by   Staphylococcus aureus   or   Pseudomonas aeruginosa  ,the methanesulfonic acid gatixincin and positive drug  gatiffincin exerted similar effect.Conclusion  There is no significant difference in the antibacterial activity between methanesulfonic acid gatixincin and gatiffincin.