Abstract: Objective To investigate the Acinetobacter baummanii in ICU and its drug-resistant phenotype and genotype. Methods Acinetobacter baummanii was isolated every two weeks in surgical ICU, neurological ICU and respiratory ICU in our hospital from October 2010 to October 2011. The antibiotic sensitivity was tested and the drug-resistant genes (IMP, SIM, VIM, OXA-23, 24, 51, and 58) were detected. Results A total of 7 878 samples were collected from 3 ICUs, from which 229 Acinectobacter baummanii strains were isolated. The rate of Acinectobacter baummanii strains isolated in respiratory ICU was signifcantly higher than those isolated in surgical ICU and neurological ICU (5.41% vs 2.39%, 5.41% vs 2.56%, P＜ 0.001). The resistance of Acinectobacter baummanii strains to polymyxin was 67% and rather low to other antibiotics. The detection rate of IMP, VIM, and OXA -51, OXA-23, OXA-58 was 20.52%, 11.36%, and 32.75% (75/229), 31.44% (72/229), 3.49% (8/229), respectively. No SIM, OXA-24, AmpC and CTX-M genes were detected. Conclusion The contamination of Acinectobacter baummanii is severe in ICU and its drug resistance is high, daily disinfection of ICU should thus be strengthened in order to prevent outbreak of Acinectobacter baummanii infection.