Objective To investigate the content and its distribution of dynamic change of nuclear factorκB（NF-κB）of lung tissues from hydrogen sulfide（H2S）acute poisoned rats and the intervention effects of ulinastatin（UTI）on it.Method 88SD rats were randomly divided into control group

H2S group and H2S+UTI group and the content and distribution of NF-κB in all groups were observed with the method of immunohistochemistry.Results The protein expressions of NF-κB in the lung tissues of rats in the H2S group increased mor significantly than the control group at the time points of 2

6

12

24and 48hours（P<0.05）;the protein expressions of NF-κB in the H2S+UTI group were significantly lower than H2S group at the same time points of 2

6

12

24and 48hours（P<0.05）.NF-κB protein could not only express in alveolar epithelial cells

but also distribute in the tracheal epithelial cells and inflammatory infiltration cells（mainly in neutrophils and macrophages）.Conclusion The expression of NF-κB in the lung tissue from rats with H2S inhalation toxicity and acute lung injury increases in the early stage but the treatment of UTI intervention can significantly reduce its expression.