〔Abstract〕 Objective To investigate the efficacy of two-level non-invasive positive pressure ventilator in the treatment of obstructive sleep apnea hypopnea syndrome (OSAS) complicated with chronic obstructive pulmonary disease (COPD). Methods A total of 82 patients with OSAS complicated with COPD treated in Nanhai Fifth People's Hospital of Nanhai District, Foshan City from January 2019 to May 2021 were randomly divided into control group and observation group, with 41 cases in each group. The control group was treated with continuous positive airway pressure (CPAP), and the observation group was treated with two-level non-invasive positive pressure ventilator (BIPAP). The changes of blood gas analysis indexes, polysomnography monitoring (PSG) indexes and lung function indexes were compared between the two groups. Results After treatment, the arterial partial pressure of oxygen (PaO2) and pH of the observation group were significantly higher than those of the control group, and the arterial partial pressure of carbon dioxide (PaCO2) was significantly lower than that of the control group, and the differences were statistically significant (P < 0.05); The lowest blood oxygen saturation (SpO2Low) after treatment was not significantly different from that of the control group (P > 0.05), but the apnea hypopnea index (AHI) and the longest apnea time of the observation group after treatment were less than those of the control group, the differences were statistically significant (P < 0.05); There were no significant differences in the levels of FVC, FEV1, FEV1/FVC between the two groups after treatment (P > 0.05). Conclusion BIPAP in the treatment of OSAS combined with COPD can effectively correct blood gas analysis indexes, improve hypoxemia, reduce the number of apneas, and improve lung function. It has positive clinical significance.