Abstract: Objective To establish an modified rabbit model of the acute lung injury induced by cardiopulmonary bypass (CPB) with ascending aorta and right atrium catheterization and detect the changes in serum tumor necrosis factor-α (TNF-α) level after modeling. Methods Ten healthy adult male New Zealand rabbits were randomly selected to establish CPB models. The model establishment was deemed successful if the rabbits survived for over 4 h with stable heart beat after termination of CPB. The vital signs of the rabbits were recorded after anesthesia (T1), before CPB (T2), at 15 after blocking the ascending aorta and pulmonary artery (T3), immediately after re-opening of the ascending aorta and pulmonary artery (T4), and at 1 (T5) and 4 (T6) after CPB. Arterial blood gas (ABG) was monitored at T2, T4 and T6 and the serum levels of TNF-α were also detected with ELISA. Results Nine rabbit models of CPB with acute lung injury were successfully established. During the operation, the MAP was maintained at a level above 55 mmHg, HCT significantly decreased from (30.18±2.88)% at T2 to (17.73±1.95)% at T4 (P<0.05), and plasma lactate level increased significantly from 3.65±1.13 mmol/L at T2 to 9.36±1.28 mmol/L at T4 (P<0.05). The oxygenation index (PaO2/FiO2) at T6 was significantly lower than that at T2 (281.64±55.76 vs 468.36±56.28 mmHg, P<0.05). The serum levels of TNF-α were significantly increased (P<0.05) and obvious lung interstitial edema and inflammatory cell infiltration occurred after CPB establishment. Conclusion The modified rabbit model of CPB with acute lung injury is stable and reliable and can be used for studying acute lung injury induced by CPB.