Abstract: Objective To investigate the effect of clearance time of condensate in ventilator pipes of intensive care unit (ICU) on bacterial infection of respiratory tract. Methods A total of 96 patients with mechanical ventilation for more than 48 h in ICU of Chuzhou Integrated Hospital of Traditional Chinese and Western Medicine were randomly divided into 6 h group and 12 h group, with 48 patients in each group. The condensate in the respiratory pipeline was cleaned up every 6 h (6 h group) or 12 h (12 h group) after mechanical ventilation. The bacterial contamination rate of condensate and pathogenic bacteria in condensate of the two groups were compared, and the incidence of ventilator associated pneumonia (VAP) in the two groups was analyzed. Multivariate logistic regression was used to analyze the risk factors of condensate pollution and VAP. Results The contamination rate of condensate in the 6 h group was significantly lower than that in the 12 h group (14.58% vs. 56.25%, P<0.01). The main bacteria in the condensate were Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. The incidence of VAP in the 6 h group was significantly lower than that in the 12 h group (4.17% vs. 20.83%, P<0.05). The coincidence rate of pathogenic bacteria in condensate with pathogenic bacteria in patients in 6 h group and 12 h group was 100% and 90%, respectively. Condensate cleaning time was a risk factor for condensate pollution in ventilator pipelines (P<0.01). Condensate cleaning time, condensate pollution and APPACHE II score at admission were risk factors for VAP (P<0.01). Conclusions The condensate pollution in the ventilator pipeline of ICU patients mainly occurs at 6-12 h, and the condensate should be cleaned every 6 h, which can effectively reduce the incidence of VAP in ICU patients.