Abstract: Weightlessness or simulated weightlessness can lead to some changes of vascular structure and functions regionspecifically and has an influence on the morphology and ultrastructure of vascular endothelial cells, causing expression changes of some related genes and molecules. Current studies show that multiple mechanisms are involved in these changes such as ion channels，the expression changes of eNOS and iNOS as well as cytoskeletal rearrangement. Some measures such as intermittent artificial gravity have been applied to counter the morphological and functional changes of vessels and vascular endothelial cells which result in cardiovascular deconditioning.