Objective To observe the protective effect on rat lung by using N-acetyl-L-cysteine(NAC) a inhibiter of nuclear factor-kappa B (NF-κB) in the period of reperfusion. Methods Twenty-four rats were randomly divided into a control group and a trail group.The harvested lung blocks of 12 rats were flushed with and stored in the low-potassium-dextran (LPD) solution at 4℃ for 16 hours. The isolated rat lung reperfusion models were established and the donor lungs were perfused for 1 hour. NAC was used in the trail group but normal saline was used in control group. Partical pressure of oxygen in artery (PaO2), peak airway pressure (PawP) were measured at every 15 min intervals during reperfusion. After reperfusion, the lung tissue wet-to-dry(W/D)ratio, and myeloperoxidase(MPO) activity were obtained. The protein and mRNA expressions of intercellular adhesion molecule-1(ICAM-1), NF-κB were also observed by using immunohistochemistry and semi-quantitative RT-PCR at the end of reperfusion. Results The level of decreased PaO2 and increased PawP in trail group were lower than those in control group at every interval time the sample obtained after reperfusion in 60 min. (Plt;0.01 or lt;0.05). After reperfusion the W/D,MPO, the protein and mRNA expressions of ICAM-1, NF-κB were decreased evidently in trail group than those in control group(Plt;0.01 or lt;0.05). Conclusion Using NAC in the period of reperfusion, can effectively inhibit the expression of NF-κB and ICAM-1,further improve lung respiratory functions.