ObjectiveTo investigate the differences in distribution and characteristics of the class 1 integron (IntⅠ) between multidrug resistant (MDR) and susceptible Pseudomonas aeruginosa (PA), and to evaluate whether IntⅠ was associated with the formation of MDR of PA.MethodsPositive rate of IntⅠ in 67 MDR and 62 susceptible isolates from clinical samples were detected by polymerase chain reaction(PCR), and integrated gene cassettes in IntⅠ positive strains were also identified by PCR.Results32(47.76%) isolates with MDR phenotype were IntⅠ positive but only 1(1.61%) isolate with susceptible phenotype was IntⅠpositive, the distribution of IntⅠin MDR isolates was significantly higher than susceptible ones(χ2=36.02,P<0.05). The gene cassettes in MDR group carried large fragments, but the susceptible isolates carried an empty one.ConclusionPositive rate of IntⅠ in MDRPA is high and may be related with MDR of PA.