Most young people with stroke do not have the common risk factors of cerebrovascular disease， and the etiology is mainly uncommon or unclear. As the overall incidence of stroke in young people is increasing year by year， and the recurrence rate of stroke is also related to the prevention and control of the etiology. Therefore， it is particularly important to conduct in-depth research on the etiology of cryptogenic ischemic stroke（ CIS） in young people and to prevent and treat it. This paper reviews the research progress of the etiology of CIS in young people reported in recent years.