Abstract: Objective To analyze pathogenic bacteria distribution and risk factors of ventilator-associated pneumonia(VAP) in patients,who were treated with mechanical ventilation in the First Affiliated Hospital of Anhui Medical University from September 2015 to August 2016, so as to provide the basis of the early prevention and control of ventilator associated pneumonia. Methods A retrospective analysis was conducted among the patients who were treated with mechanical ventilation in the First Affiliated Hospital of Anhui Medical University from September 1, 2015 to August 31, 2016. The pathogenic bacteria distribution and drug resistance rate were studied. Results A total of 751 patients were treated with mechanical ventilation and 303 strains of pathogenic bacteria were isolated. Most of bacteria samples were obtained from sputum (81.85%), blood (6.93%) and urine (2.64%).Gram-negative bacteria, gram-positive bacteria and fungi accounted for 84.61%, 6.93% and 8.91%, respectively. According to the result of drug susceptibility tests, Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli were four main types of gram-negative bacteria, and the main type of gram-positive bacteria was Staphylococcus aureus. The risk factors of VAP included patients' indwelling gastric tube, more than three types of antibiotics application, extension of duration of mechanical ventilation and ICU length of stay. Conclusions Gram-negative bacteria accounted for the largest proportion of pathogenic bacteria in patients treated with ventilator. For the purpose of instructing antibiotics selection in clinical practice, it is necessary to explore the rate of drug resistance and other risk factors.