ObjectiveTo study the incidence of ventilatorassociated pneumonia(VAP)and antimicrobial resistance of pathogens in an intensive care unit(ICU).MethodsThe occurrence of VAP in hospitalized patients with mechanical ventilation >48 hours between January 2011 and December 2012 were investigated, species and antimicrobial resistance of pathogens causing early onsetVAP (EVAP, mechanical ventilation≤4 d）and lateonset VAP（LVAP，mechanical ventilation ＞4 d） were compared.ResultsA total of 176 patients were investigated,incidence of VAP was 44.32%（78 cases）；With the prolongation of mechical ventilation，incidence of VAP increased gradually (χ2=52.561，P＜0.001）.The incidence of LVAP was significantly higher than EVAP (58.33% ［70/120］ vs 14.29% ［8/56］）（χ2=30.02，P＜0.001）.A total of 178 pathogens were isolated, gramnegative bacteria,grampositive bacteria and fungi were 104（58.43%）,46（25.84%）,and 28（15.73%） isolates respectively； 97(54.49%) multidrugresistance/pandrug resistance organisms (MDRO) were isolated. MDRO isolation rate in LVAP patients was higher than EVAP patients（［58.86%，n=93］ vs ［20.00%，n=4］）,resistance rate of major pathogens causing LVAP was significantly higher than EVAP patients(all P<0.05).Fungi infection only occurred in LVAP patients, the total antimicrobial resistance rate was 12.14%.ConclusionThe prolongation of mechanical ventilation can increase the incidence of VAP, and resistance rate of pathogen in LVAP is high.