OBJECTIVE： To investigate the clinical etiology， serum type and drug resistance of lung cancer complicated with pulmonary Haemophilus influenzae （Hi） infection， in order to provide reference for infection prevention and rational drug use. METHODS： Clinical data of 8 025 inpatients with lung cancer complicated with pulmonary infection in our hospital from Jan. 2009 to Jun. 2016 were collected， and the clinical etiology of pulmonary Hi infection was analyzed. The slide agglutination method was used for serotyping， nitrocefin slip method was used to detect β-lactamase， K-B method was used for drug sensitivity test， WHONET 5.6 software was used to deal with the results of drug sensitivity test. RESULTS： Eleven factors as age， clinical classification， invasive operation， surgery， radiotherapy and chemotherapy， hospitalization time， use of broad-spectrum antibiotics or hormones and other were closely related to pulmonary Hi infection in lung cancer patients （P＜0.05 or P＜0.01）. Among 8 025 specimens，104 strains of Hi were detected with detection rate of 1.30％. Serum type NTHi accounted for 44.23％. Separable strains were mainly b type （22.12％）， followed by f type （17.31％） and a type （11.54％）. Among 104 strains of Hi， 56 strains of β-lactamase were detected with enzyme-producing rate of 53.85％. Drug resistance of 104 strains of Hi to ampicillin， amoxicillin， compound sulfamethoxazole and chloramphenicol were all higher than 35％； drug resistance of Hi to β-lactamase inhibitors， cephalosporins， carbapenems， azithromycin and other antibiotics were all lower than 20％. Drug resistance of β-lactamase producing stains to ampicillin， amoxicillin， compound sulfamethoxazole and chloramphenicol were all higher than those of non-producing strains， with statistical significance （P＜0.01）. There was no statistical significance in drug resistance to other antibiotics between producing stains and non-producing strains （P＞0.05）. CONCLUSIONS： The clinical etiology of pulmonary Hi infection in patients with lung cancer is complicated. The serum type of the isolate is mainly NTHi； enzyme production situation is not optimistic， but Hi keeps a low rate of drug resistance to most antibiotics. β-lactamase inhibitors， cephalosporins， carbapenems and azithromycin are first choice for the treatment of Hi infections.