【Abstract】 Objective To observe the effect of noninvasive mechanical ventilation on cardiac function and electrocardiogram (ECG) of patients with chronic obstructive pulmonary disease (COPD) complicated with respiratory failure. Methods 86 patients with COPD complicated with respiratory failure were divided into the observation group and the control group by random number table method, 43 cases in each group. The control group was given conventional treatment, while the observation group was given noninvasive mechanical ventilation, on the basis of conventional treatment. The arterial blood gas indexes (HR, RR, PH, PaO2, PaCO2), cardiac function indexes (LVEF, cTnI, BNP, ProBNP), APACHE score, changes in P wave of ECG, the length of hospital day, times of tracheal intubation, hospitalization expenses and incidence of related complications were compared between the two groups. Results After treatment, the HR, RR, PaCO2, cTnI, BNP, ProBNP, APACHE score, Pmax and Pwd of the observation group were significantly lower than those of the control group (P＜005), while PH, PaO2 and LVEF were significantly higher than those of the control group (P＜005). The length of hospital stay, times of tracheal intubation and hospitalization expenses of the observation group were significantly shorter and less than those of the control group (P＜005). There was no significant difference in the incidence of complications between the two groups (P＞005). Conclusion Noninvasive mechanical ventilation can improve the ventilation efficiency, blood gas analysis indexes and cardiac function indexes in patients with COPD complicated with respiratory failure. It is noninvasive and convenient, with few complications.