ObjectiveTo evaluate systematically the effect of ventilator circuit changes on incidence of ventilatorassociated pneumonia(VAP). MethodsLiteratures about the effect of ventilator circuit changes on occurrence of VAP were searched from PubMed, Cochrane Library, CNKI, VIP, and Wanfang database, incidence of VAP in patients who received circuit changes at different intervals was compared, odds ratio (OR) and 95%CI were as effect index of the study, RevMan 5.2 software was used for data analysis. ResultsA total of 12 literatures were included, including 18 003 patients using ventilators. According to the interval of ventilator circuit changes, patients were divided into 1day group (n=191), 2day group(n=8 932), 3day group(n=228), and 7day group(n=8 652). Meta analysis showed that circuit changed every 7 days had a lower risk of VAP than that changed once every day (OR, 3.72［95%CI, 1.50，9.23］）, there was no significant difference in risk of VAP between 7day group and 2day group (OR, 1.17［95%CI, 1.00，1.37］）as well as 7day group and 3day group(OR, 0.77 ［95%CI, 0.49，1.23］）. ConclusionPatients who received circuit changes every 7 days have a lower risk of developing VAP than those who received circuit changes once per day, so change the ventilator circuit in patients with mechanical ventilation every 7 days is more reasonable.