Cerebral amyloid angiopathy（ CAA） is a cerebral small-vessel disease characterized by the deposition of amyloid β-protein in the cerebral vascular wall， which is a major cause of cerebral hemorrhage， dementia， and cognitive decline. In recent years， the role of the immune system in CAA has gradually attracted attention. Immune cells not only participate in the clearance of amyloid β-protein， but may also exacerbate the pathological process of CAA through inflammatory responses. This review summarizes the various mechanisms of the immune system in CAA， including the role of immune cells in amyloid β-protein clearance， the impact of immune responses on vascular injury and inflammation， and the potential of immunomodulatory therapeutic strategies， with the aim of providing new insights and targets for the early diagnosis， risk stratification， and treatment of CAA.