Objective To investigate the suppression effect and mechanism of Astilbin on lung allograft rejection in rats, in order to know the function of Astilbin on rats’ lung acute rejection. Methods The model of rat left lung transplantation was set up. Sixty lung transplanted rats were divided into two groups randomly, control group: rats were fed with normal saline 1ml per day, experimental group: rats were fed with Astilbin 1mg/kg per day. Survival time, transforming rate of T cells in spleen, activity of interleukin 2 (IL-2) in spleen lymph cells and apoptosis of T cells were observed. Changes in ultrastructure of pulmonary arteries were observed by electron microscope. Results The survival time in experimental group was prolonged than that in control group (25.4±2.1 d vs. 13.4±1.2 d;t=2.042, Plt;0.05）. Transforming rate of T cells of spleen in experimental group was significant lower than that in control group (23 465.8±8 783.4 cpm vs. 74 567.3±12 874.6 cpm; t=2.284，Plt;0.05）.Activity of IL-2 of spleen lymph cells in experimental group was significant lower than that in control group (425±2.65U/ml vs. 23.46±1.82U/ml; t=3.165, Plt;0.01).Effectively derive apoptosis of activated T cells in acute rejection were observed in experimental group, the ultrastructure of pulmonary arteries showed attenuated injury in experimental group. Conclusion Astilbin decreased the IL-2 concentration in plasma and induced the apoptosis in activated T cells, then suppressed the acute rejection of lung allograft and prolonged the survival period of lung transplantation rats.