OBJECTIVE： To confirm the regularity of drug resistance and main mechanism of Acinetobacter baumannii in ICU of our hospital， and to provide reference for rational drug use in clinic. METHODS： Ninety strains of A. baumannii were collected from ICU of our hospital during Jan. 2015-Dec. 2016. Drug resistance of A. baumannii to 10 kinds of commonly used β-lactam antibiotics was determined by two-fold dilution method. The presence of β-lactamase genes was detected by PCR. RESULTS： Totally 90 strains of A. baumannii were separated from sputum specimen （46 strains， 51.11％）， purulent fluid specimen （13 strains， 14.44％） and blood specimen （12 strains， 13.33％）， etc. The resistance rates of A. baumannii to penicillins， three or four-generation cephalosporins were in high level （≥50％）， while that of it to carbapenems was in low level relatively （＜30％）， that of it to inhibitor compound preparation containing enzyme as cefoperazone/sulbactam was the lowest （11.11％）. β-lactamase genes were detected in 68.89％ of strains， and there were 42 strains of AmpC， 8 strains of CTX-M2， 30 strains of TEM-1， 20 strains of SHV-5， 48 strains of PER-1， 12 strains of OXA-23 genes； detection rates of them were 46.67％， 8.89％， 33.33％， 22.22％， 53.33％， 13.33％， respectively. MIC50 of strains without above genes were 1-256 μg/mL， and MIC50 of strains with above genes were 2-1 024 μg/mL. There were 19 strains with 1 kind of above genes， 15 strains with 2 kinds of above genes， 26 strains with 3 kinds of above genes； MIC50 of them were 2-512， 2-1 024， 4-1 024 μg/mL， respectively. CONCLUSIONS： A. baumannii were mainly from sputum specimen in ICU of our hospital， and resistant rate of commonly used β-lactam antibiotics is in high level generally. β-lactamase genes were mainly PER-1 and AmpC； the more gene types， the higher resistant rate of strains to β-lactam antibiotics. It is necessary to further detect the homlolgy of A. baumannii， conduct hospital environment disinfection， strengthen drug resistance monitoring， enhance clinical application management of antibiotics， and select antibiotics rationally according to drug sensitivity test so as to reduce the occurrence of drug-resistant A. baumannii.