目的　观察模拟失重对家兔股静脉壁超微结构的影响 ,了解模拟失重下股静脉血管的重塑情况。　方法　建立头低位 -2 0°倾斜的模拟失重家兔模型。 2 4只雄性健康新西兰兔 ,随机分为模拟失重 2 1d组、模拟失重 10 d组和对照组 ,每组 8只。用透射电镜观察兔股静脉壁的超微结构。　结果　模拟失重组家兔股静脉内皮细胞细胞器减少 ,线粒体溶解、消失 ;空泡变性增多并可见吞噬体 ;内弹力板变薄且有断裂 ;平滑肌层变薄 ,部分平滑肌细胞有变性 ,间质增多。模拟失重 2 1d组较模拟失重 10 d组变化更明显。　结论　在模拟失重影响下 ,家兔股静脉壁结构发生血管重塑性变化 ,呈萎缩性改变 ,模拟失重时间越长 ,改变越明显 Objective To observe the effect of simulated weightlessness on the ultrastructure of rabbit femoral vein and to understand the remodeling of femoral vein under simulated weightlessness. Methods A rabbit model of simulated weightlessness with a -2 0 ° head tilt was established. Twenty-four male New Zealand white rabbits were randomly divided into 2 groups: simulated weightlessness 2 ld group, simulated weightlessness 10 d group and control group, with 8 in each group. The ultrastructure of rabbit femoral vein was observed by transmission electron microscope. Results In the simulated weightlessness group, the organelles in the femoral vein endothelial cells of rabbits decreased, mitochondria dissolved and disappeared, vacuoles degenerated and phagosomes were seen, the inner elastic plate became thin and ruptured, the smooth muscle layer became thinner, some of the smooth muscle cells degenerated and interstitial increased . Compared with the simulated weightlessness at 10 d, the changes of simulated weightlessness in 21d group were more obvious. Conclusion Under the influence of simulated weightlessness, the changes of vascular remodeling of rabbit femoral vein wall structure showed atrophic changes, the longer the simulated weight loss, the more obvious the change