Abstract: OBJECTIVE To investigate the etiological characteristics of postoperative pulmonary infections in lung cancer patients and explore the risk factors so as to provide guidance for clinical prevention and treatment. METHODS The clinical data of 350 lung cancer patients who received surgical procedures in the hospital from Jan 2013 to Jan 2017 were retrospectively analyzed.The incidence of postoperative infections and distribution of pathogens were statistically analyzed, and the univariate analysis and multivariate logistic regression analysis were performed for the influencing factors for the postoperative infections. RESULTS Of the 350 lung cancer patients, 34 had postoperative pulmonary infections, with the infection rate 9.71%, of whom 5 had mild infections, 18 had moderate infection, and 11 had severe infections.A total of 64 strains of pathogens were isolated from the 34 patients with pulmonary infections, of which 42 (65.63%) were gram-negative bacteria, 17 (26.56%) were gram-positive bacteria, and 5 (7.81%) were fungi.The result of the univariate analysis showed that the patients with advanced age, diabetes mellitus, invasive operations, chronic obstructive pulmonary disease, postoperative pains of incision and long operation duration were more likely to have nosocomial infections (P＜0.05).The variables with statistical significance were introduced into Logistic regression model for multivariate analysis, the result of which indicated that the advanced age, diabetes mellitus, chronic obstructive pulmonary disease and pain of incision were the independent influencing factors for the postoperative pulmonary infections (P＜0.05). CONCLUSION Klebsiella pneumoniae is the predominant species of pathogen causing the postoperative infections in the lung cancer patients, the postoperative pulmonary infections may be remarkably associated with the advanced age, diabetes mellitus, chronic obstructive pulmonary disease and pain of incision.It is necessary for the hospital to add sensitive antibiotics for treatment of K.pneumoniae infections during the prophylactic use of antibiotics and take effective prevention measures aiming at the risk factors so as to reduce the incidence of postoperative pulmonary infections.