Abstract: OBJECTIVE To investigate the characteristics and influencing factors of nosocomial infection pathogens in patients with non-small cell lung cancer (NSCLC) undergoing chemoradiotherapy. METHODS The 260 cases of NSCLC patients undergoing chemotherapy and radiotherapy admitted to our hospital during Jan. 2013 to Dec. 2016 were selected. Bacterial culture and identification were conducted, and clinical data of the patients were investigated. Univariate and multivariate logistic regression were used to analyze the independent risk factors. RESULTS Among the 260 cases of NSCLC patients, 31 cases (11.92%) had nosocomial infection, dominated by respiratory tract infection, with 13 cases accounting for 41.94%. From the 31 cases of nosocomial infection, 43 strains of pathogenic bacteria were isolated, among which 27 strains were gram-negative bacteria accounting for 62.79%, and 14 strains were gram-positive bacteria accounting for 32.56%. Multivariate logistic regression analysis showed that age, tumor stage, malnutrition, smoking, invasive procedures, length of hospital stay and prophylactic antibiotics were the risk factors for nosocomial infection in NSCLC patients (P<0.05). CONCLUSION Gram-negative bacteria are the main pathogens of nosocomial infection in patients with NSCLC undergoing radiotherapy and chemotherapy, and nosocomial infection is affected by many factors. Therefore, rational use of antibiotics and targeted preventive measures are needed to reduce the infection rate.