Objective To investigate the therapeutic effect of non-invasive positi e pressure ventilation (NIPPV) in the treatment of patients with acute exacerbations of chronic obstructive pulmonary disease(AECOPD).Methods 68 AECOPD patients with type Ⅱ repiratory failure were randomly divided into control group and treatment group.The control group was treated by conventional therapy alone and the treatment group was given conventional therapy combined with NIPPV.The levels of power of hydrogen (pH),partial pressure of carbon dioxide in artery(PaCO2),arterial oxygen tension(PaO2),heart rate and repiratory rate were compared between the two groups.The mean length of patient stay,the frequency of tracheal intubation and the hospital mortality were analyzed after discharge from the hospital.Results Before treatment,the arterial blood gas analysis showed that the pH,PaCO2 and PaO2 had no significant differences between the two groups(all P ＞ 0.05).After treatment,compared with the control group,the levels of pH,PaCO2 and PaO2 were obviously improved(all P ＜0.05).The mean length of patients stay in the treatment group was significantly shorter than the control group(P ＜ 0.05).The frequency of tracheal intubation of the treatment group was significantly lower than the control group(P ＜ 0.05).The hospital mortality was lower in the treatment group,but the difference between the two groups was not significant (P ＞ 0.05).Conclusion NIPPV for treating the AECOPD can improve the arterial blood gas analysis,decrease the need of tracheal intubation and shorten hospitalization time.