Abstract: OBJECTIVE To investigate the evolution of antibiotic resistance of Acinetobacter baumannii isolated from inpatients with bloodstream infections to 11 kinds of antibiotics, so as to provide epidemiological data for the rational use of antibiotics. METHODS Clinical distribution characteristics and in vitro antibiotic susceptibility of A. baumannii isolated from inpatients with bloodstream infections from Jan. 2009 to Dec. 2014 to 11 kinds of antibiotics were retrospectively analyzed. The WHONET5.6 software was used for data statistical analysis. RESULTS A total of non-duplicated 136 strains of A. baumannii were isolated from patients with bloodstream infections from 18 departments from 2009 to 2014, and the top 3 departments were intensive care unit, respiration, and neurosurgery. The drug resistant rates of A. baumannii to ampicillin/sulbactam, piperacillin/tazobactam, ceftazidime, cefepime, imipenem, meropenem were all above 70.00%. Totally 102 (75.0%) isolates were found multi-drug resistance(MDR) and the MDR strains was increased with years from 2009-2014. CONCLUSION The detection rate of A. baumannii was gradually increased, detection rate multidrug-resistant bacteria was also increased year by year, and the overall trend of drug resistance was increased, therefore, clinical antibiotics should be selected rationally to avoid the occurrence of multidrug-resistant bacteria and pan-resistant bacteria.