Objective To explore the causes of rising carbapenem resistance in Acinetobacter baumannii isolates by analysis of the carbapenemase genotypes in A .baumannii .Methods WHONET 5 .4 was used to analyze the changing resistance profile of A .baumannii isolates over years .A total of 320 carbapenem‐resistant A .baumannii isolates were collected from the patients in an intensive care unit from January 2008 to December 2012 .All strains were identified and tested by VITEK 2 for their susceptibility .The metallo‐β‐lactamases genes and OXA carbapenemase genes were investigated by polymerase chain reaction . Results The resistance rate of A .baumannii isolates to meropenem and imipenem increased rapidly from 10 .8% to 80 .4% and from 13 .5% to 83 .5% during the period from 2008 and 2012 .The prevalence of blaOXA‐23and ISAba1‐associated blaOXA‐23genes increased from 25 .0% to 97 .1% .No metallo‐β‐lactamase encoding genes were detected .Conclusions Our results indicate that the rising carbapenem resistance in the A . baumannii isolates in our intensive care unit may be associated with the high prevalence of blaOXA‐23 and IS A ba1‐associated blaOXA‐23 genes .