Objective To estimate the application value of head-neck CT angiography（ CTA） and whole brain CT perfusion（ CTP） in patients with chronic cerebral ischemia by the correlation comparison study of head-neck CTA and brain CTP. Methods A total of 150 patients' CTA and CTP were analyzed for their correlations with the distribution of perfusion region， responsible blood vessels and perfusion abnormalities. Results The responsible vessels of 98.72% perfusion abnormal region were moderate vascular stenosis. With the aggravation of the degree of the stenosis of the responsible vessels， the proportion of abnormal region of perfusion was significantly increased. The degree of responsible vascular stenosis was moderately positively correlated with the staging of CTP in the pre-infarction stage. Conclusions Combined with the results of headneck CTA and whole brain CTP， the degree of chronic ischemia in patients with chronic cerebral ischemia can be comprehensively evaluated， which is more conductive to the selection of clinical treatment.