ObjectiveTo explore the clinical significance of procalcitonin(PCT) in guiding the optimizing antimicrobial treatment strategy in ventilatorassociated pneumonia(VAP). MethodsSixty patients  receiving mechanism ventilation for ≥48 hours in an intensive care unit between November 2011 and  April 2013 were randomly divided into control group (n=29) and trail group (n=31), patients in control group stopped antimicrobial use according to guideline, patients in trail group stopped antimicrobial use according to serum procalcitonin level, duration of antimicrobial use and  mechanical ventilation between two groups were compared. ResultsDays of mechanical ventilation,length of ICU stay, mortality rates between two groups were not significantly different(all P>0.05); antimicrobial days  in trail group was significantly less than control group（［10.70±3.78］ d vs ［13.93±3.03］ d)（t=4.484；P＜0.001）. ConclusionSerum procalcitonin level plays an important  role in the rational use of antimicrobial agents in patient with VAP.