Abstract: Objective To observe the clinical effect of non-invasive bi-level positive airway pressure ventilation in the treatment of chronic obstructive pulmonary disease(COPD)complicated with respiratory failure. Methods Totally 60 COPD patients complicated with respiratory failure were selected and randomly divided into observation group(n=30)and control group(n=30). The control group was treated by conventional therapies such as low flow oxygen inhalation with nasal catheter and anti-infection therapy, while the observation group was treated with non-invasive bi-level positive airway pressure ventilation. The clinical efficacy, arterial partial pressure of oxygen ［p_a(O₂)］, arterial partial pressure of carbon dioxide ［p_a(CO₂)］ and pH value before treatment and 24, 48 h after treatment were compared between the two groups. Results The effective rate of the observation group was 93.33%, which was significantly higher than 73.33% of the control group(P<0.05). After 24 and 48 hours of treatment, the p_a(CO₂)level in the observation group was significantly lower than that in the control group, while the pH value and p_a(O₂)level were significantly higher than those in the control group(P<0.05). Conclusion Non-invasive bi-level positive airway pressure ventilation can effectively improve the blood gas analysis indexes of COPD patients with respiratory failure, relieve fatigue of respiratory muscle, and promote the recovery of patients.