OBJECTIVE：To provide reference for clinical treatment of Acinetobacter baumannii infection and rational use of antibiotics. METHODS ：By retrospective analysis ，64 500 strains of bacteria were isolated from the inpatients of our hospital during Jan. 2015 to Dec. 2018. WHONET 5.6 software was used to analyze the detection rate ，specimen type ，departments of A. baumannii. The resistance of A. baumannii to 18 commonly used antibiotics in 4 years was analyzed by RxC table χ 2 test. RESULTS：A total of 2 072，2 040，2 017 and 2 143 strains of A. baumannii were isolated during 2015-2018，accounting for 12.85％，13.38％，13.60％，11.71％ of positive specimens. The main specimen types of 8 272 strains of A. baumannii were sputum（4 368 strains，52.81％），pus（1 106 strains，13.37％），ascites（804 strains，9.72％）. The main departments were burn department（1 605 strains，19.40％），hepatobiliary department （1 200 strains，14.51％），brain surgery department （977 strains， 11.81％）. The drug resistance rate to 18 kinds of antibiotics showed a wave-like decreasing trend （P＜0.001）. In 2018，drug resistance rate to ampicillin and aztreonam was more than 80％，and that to ampicillin/sulbactam ，ceftazidime，levofloxacin， Compound sulfamethoxazole ，gentamicin，amikacin，tobramycin and tegacyclin was less than 50％ ，among which the drug resistance rate to amikacin and tegacyclin were 14.7％ and 0，respectively. CONCLUSIONS ：There is no significant change in the number of isolates and detection rate of A. baumannii in our hospital between 2015 and 2018. The bacteria mainly cause respiratory tract infection. Amikacin or tegacyclin are recommended for treatment.