Objective:To explore the pretection of small dosage desamethasone to pulmonary function on acute lung injury model.Methods:54 male SD rats were divided randomly into control group

injury group and therapeutic group.Major observed marker consisted of count of cell sum

total protein level and TNF-α level of bronchoalveolar douche solution.Secondary marker consisted of lung coefficient

PAO2

TNF-α level in blood serum and histopathologic examination.Results: Alveolar texture in therapeutic group existed yet

but alveolar interval increased thickness

neutrophilic granulocyte infiltration relieved obviously

and a little bleeding in alveolar cavity.PAO2 in therapeutic group was higher than that of injured group(P <0.05).A significant difference existed between therapeutic group and other groups in lung coefficient

total protein level and cell sum of bronchoalveolar douche solution(P <0.05).and a obvious difference in TNF-α level also existed between therapeutic group and other groups in blood serum in 2 hours and in bronchoalveolar douche solution in 2 and 6 hours(P<0.05).Conclusion: Small dosage desamethasone could protect injured lung texture.