Abstract： Objective To discuss the effects of bone marrow-derived mesenchymal stem cells (MSCs) on vascular endothelial growth factor (VEGF) in lung tissue and in plasma, and extra-vascular lung water at the early stage of smog inhalation injury. Method The rabbit model of smog inhalation injury was established by using home-made smog generator, and the rabbit models were randomly(random number) divided into control group (group S, n = 32) and MSCs treatment group (group M, n = 32). Ten mL phosphate-buffered saline (PBS) was injected into ear marginal vein immediately after injury in rabbits of group S. The third generation of MSCs 1/10/10 mL PBS was injected into ear marginal vein immediately after injury in rabbits of group M. The levels of VEGF in peripheral blood and lung tissue were neasured 0 h,2 h,4 h and 6 hours after injection respectively, and analyzed. The right lung of rabbits was taken out to measure and calculate lung water mass fraction after experiment.Results In lung tissue, the levels of VEGF decreased gradually in group S (P ＜ 0.05), and though the levels of VEGF in lung tissue appeared with significant decreasing trend in group M (P ＜ 0.05), they were still higher than those of group S at corresponding intervals ( P ＜ 0.05). In peripheral blood, the levels of VEGF increased gradually in group S ( P ＜ 0. 05), and the levels of VEGF in group M appeared with markedly increasing trend ( P ＜ 0.05),but they were lower significantly than those in group S at corresponding intervals ( P ＜ 0.05). Conclusions MSCs engraftment to the rabbits with smog inhalation injury could increase VEGF in lung tissue, decrease VEGF in plasma and reduce extra-vascular lung water, showing protective effect on smog inhalation injury to a certain extent.