Objective: To investipate the cerebral autosomal dominat arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) through the clinical features, pathology, neuroimage, and molecular genetics as well as the family tree of a case as to exploring the diagnostic method of the disease . Methods: Systematic study on the clinical manifestations, genetic site, neurologic and muscular biopsy was performed. Results: The main clinical features including poor memory and history of stroke were found. Neuroimaging examination showed multiinfarct lesions and leukoencephalopathy. Biopsy indicated the arteriolar hyalinosis, GOM and osmiophilic granule. A family history was confirmed. A mutation on the fourth exon of notch 3 gene was revealed. And no risk factors of hypertension and arteriosclerosis were found. All these features are in conformity with those of CADASIL. Conclusion: CADAIL is not rare and is possible to be defined in vivo by way of dermal biopsy, examination of gene and neuroimage characteristics.