Objective　To observe the effects of apneic oxygen insufflation (AOI) on the oxygenation and intra‑alveolar pressure of patients with one lung ventilation (OLV). Methods　Ninety patients undergoing open thoracotomy were enrolled, where 45 patients were divided into three groups according to a random number table: a control group (group A), a test 1 group (group B) and a test 2 group (group C), with 15 patients in each group; and another 45 patients were divided into three groups according to the pattern of double‑lumen tubes: a 35 Fr group (group D), a 37 Fr group (group E), and a 39 Fr group (group F), with 15 patients in each group. During OLV, the non‑ventilated lungs in groups A, B, and C were delivered with oxygen at a rate of 0, 3 and 5 L/min, respectively, and arterial blood samples were taken 1 min before OLV (T1), 30 min after the beginning of OLV (T2), and 60 min after the beginning of OLV (T3) for blood gas analysis, so as to calculate oxygenation index (OI), intrapulmonary shunt rate (Qs/Qt) and the satisfaction of surgeons towards collapsed lung. The intra‑alveolar pressure at different oxygen flow rates (2‒9 L/min) was measured in groups D, E and F after the beginning of OLV. Results　OI decreased and Qs/Qt increased in groups A, B and C at T2 and T3 compared with those at T1 (P<0.05). OI was remarkably higher in group B at T2 and higher in group C at T2 and T3 than those in group A, and Qs/Qt was significantly lower in group B at T2 and lower in group C at T2 and T3 than those in group A (P<0.05). Compared with group B, group C presented remarkable increases in OI and significant decreases in Qs/Qt at T2 and T3 (P<0.05). The intra‑alveolar pressure was lower in groups E and group F at different oxygen flow rates than that in group D (P<0.05); the intra‑alveolar pressure was lower in group F at different oxygen flow rates than that in group E (P<0.05). Conclusions　AOI at 5 L/min during OLV can maintain gas exchange to some extent in the alveoli, improve oxygenation and reduce Qs/Qt, which may be related to the intra‑alveolar pressure produced by AOI in the operated lung.