Objective To observe the expression of N-terminal pro-brain natriuretic peptide(NT-proBNP),interleukin(IL)-6 and TNF(tumor necrosis factor)-α in patients with acute lung injury(ALI),and to evaluate its value in the evaluation of severity and prognosis of lung injury.Methods A total of 76 patients with ALI treated in this hospital from August 2015 to August 2016 were enrolled in this study and 50 healthy subjects were selected as the control group.The levels of NT-proBNP,IL-6 and TNF-α in the serum of the two groups were compared and their relationship with prognosis were evaluated.Results The levels of NT-proBNP,IL-6 and TNF-α in serum of ALI group were significantly higher than those of healthy control group(P<0.05).The levels of NT-proBNP,IL-6 and TNF-α in the patients with severe lung injury were significantly higher than those in the patients with moderate lung injury(P<0.05);and each index in the patients with moderate lung injury was also significantly higher than those in the patients with mild lung injury(P<0.05).The NT-proBNP,IL-6 and TNF-α levels of the patients with ALI in the death group were significantly different from those in the survival group(P<0.05).Conclusion The levels of serum NT-proBNP,IL-6 and TNF-α can not only reflect the severity of lung injury,but also have a high predictive value for prognosis.