Abstract: AIM To observe the therapeutic effect of noninvasive bi-level positive airway pressure (BiPAP) ventilation on severe hypoxemic patients who were removed tracheal intubation after had been performed off-pump coronary artery bypass grafting (OPCAB). METHODS The clinical study included 68 severe hypoxemic patients who were removed of the tracheal intubation after the off-pump coronary artery bypass (OPCAB) surgery in our hospital between 2012 and 2016. All patients were divided into the BiPAP group (n=36) and the tracheal intubation group (n=32) based on postoperative ventilation mode. Physiological data were recorded from all the patients with heart rate (HR), blood pressure (BP), respiration (RR), cardiac functional grading, arterial blood gas analysis- including arterial partial pressure of oxygen (PaO₂) and the partial pressure of arterial carbon dioxide (PaCO₂). Postoperative complications were also analyzed. RESULTS Both in BiPAP group and tracheal intubation group, the PaO₂ was significantly improved, the PaCO₂ was decreased and pH was slight increased at the same time. And there were no significant differences in both group. In BiPAP group, HR and mean arterial pressure (MAP) were decreased after 6 hours treatment. Ventilator associated pneumonia (P<0.05), ICU stay time (P<0.01) and the time of hospital stay (P<0.01) were significantly reduced in BiPAP group than in tracheal intubation group. CONCLUSION BiPAP ventilation is a safe and effective treatment, which can quickly improve the level of arterial oxygen pressure and reduce postoperative complications.