Objective To investigate the risk factors of acute exacerbation of chronic obstructive pulmonary disease(AECOPD) combined with respiratory failure.Methods The clinical data of 120 patients with AECOPD combined with respiratory failure were retrospectively analyzed.The patients were divided into disease improved group (96 cases) and disease serious group (24 cases,including death) according to the treatment outcome.Risk factor and treatment strategies of the two groups were statistically analyzed.Results There was no significant difference in age,sex,disease course and arterial blood oxygen partial pressure(P ＞ 0.05).The body mass index,albumin,pH,successful cough and expectoration rate,nutritional support rate,and noninvasive mechanical ventilation rate in disease improved group was higher than that in disease serious group[(28.5 ± 9.8) kg/m2 vs.(23.3 ± 7.4) kg/m2,(21.4 ± 7.9) g/L vs.(19.3 ± 6.8) g/L,7.23 ± 0.20 vs.7.11 ± 0.17,79.2％ (76/96) vs.25.0％ (6/24),58.3％ (56/96) vs.33.3％ (8/24),81.2％ (78/96) vs.62.5％ (15/24)],arterial blood carbon dioxide partial pressure,mild consciousness obstacle rate,multiple drug-resistant infections rate,fungal infection rate,nasal feeding rate,hormone use time and the incidence of heart failure,pulmonary encephalopathy,hepatorenal function damage and upper gastrointestinal bleeding in disease improved group was lower than that in disease serious group [(10.08 ±1.71) kPa vs.(11.98 ± 2.03) kPa,13.5％ (13/96) vs.58.3％ (14/24),22.9％ (22/96) vs.41.7％ (10/24),0 vs.29.2％ (7/24),50.0％(48/96) vs.75.0％(18/24),(5.3 ± 1.3) d vs.(11.3 ± 3.8) d,8.3％(8/96) vs.25.0％(6/24),13.5％(13/96) vs.70.8％(17/24),28.1％(27/96) vs.41.7％(10/24),5.2％(5/96) vs.12.5％(3/24)],and there was significant difference (P ＜ 0.05).Conclusion Complicating disease,nutritional status,consciousness,capability of sputum exclusion,the degree of respiratory infection,treatment with noninv asive positive pressure ventilation,arterial gas analysis index are the correlated factors of prognosis in AECOPD combined with respiratory failure.