〔Abstract〕 Objective To study the effect of plasma exosomes on hypoxia tolerance of human microvascular endothelial cells(HMEC-1) in stroke patients and healthy controls before and after remote ischemic preconditioning(RIPC) treatment. Methods HMEC-1 cells were divided into a blank control group(Group C) and oxygen glucose deprivation(OGD) treatment group, using plasma exosomes from stroke patients before and after RIPC(S-b group, S-a group) and healthy adults before and after RIPC(C-b group, C-a group). HMEC-1 cells were incubated with a concentration of exosome(35 μg/ml) for 24 hours, followed by OGD treatment for 6 hours and reperfusion treatment for 24 hours in all groups. Water-soluble tetrazolium salt-1(WST-1) method was used to detect endothelial cell viability, caspase-3 enzyme activity was measured, and Western blot was used to detect the expression levels of zone occluden-1(ZO-1) and claudin-5.Results After RIPC in healthy adults, plasma exosomes significantly increased the cell activity of HMEC-1 cells and decreased the activity of caspase-3 enzyme in HMEC-1 cells.Conclusion After RIPC treatment, plasma exosomes reduced endothelial cell apoptosis and increased endothelial cell hypoxia tolerance.