Abstract: The purpose of the study of bone marrow mesenchymal stem cells, toxin-induced acute lung injury (ALI) rabbit model of protection. 2007-10/2008-01 experimental methods in all hospitals in the Tang Center for the completion of the laboratory. Healthy adult male rabbits, 20, of which 2 for the training culture of bone marrow mesenchymal stem cells (MSCs), more than 18 were randomly divided into three groups: endotoxin (LPS)-induced ALI model group (LPS), saline In the control group (NS group), MSCs in the treatment group. LPS group, MSCs group using tracheal instillation endotoxic established rabbit model of acute lung injury, set up after the success of the model 30min, MSCs group of rabbits by injecting the right side of the jugular vein to give bone marrow mesenchymal stem cells, LPS, and other groups to give Volume of normal saline, NS Group for more than two groups in accordance with the model, are given equal treatment to deal with normal saline, all animals to observe 48 hours after death, cell count board computing fluid in the lung cells of the total, the number of neutrophils , BCA method to calculate the total protein amount of seepage. HE left lung paraffin-embedded pathological changes were observed, said the lower left lung weight of wet and dry, wet and dry than the calculation. The results under: LPS group alveolar space and a large number of small airway inflammatory cell infiltration, edema and bleeding obvious. Alveolar clear thickening of the interval, MSCs group alveolar walls thin, only a small amount of inflammatory cells; statistical model of LPS group bronchoalveolar lavage fluid (BALF) in the number of inflammatory cells, as well as the ratio of wet and dry lung tissue protein exudation Higher than the NS group was statistically significant (P <); MSCs group than the NS group P> , no statistical significance. Conclusion MSCs through injury in the lung tissue of rabbits into a cell, thereby reducing the bronchoalveolar lavage fluid of inflammatory cells, the protein effusion, acute lung injury has a protective effect.