Objective The analysis of 128 slice spiral CT 3D imaging technology and its significance in clinical diagnosis o f cerebral infarction and intracranial aneurysm. Methods Analyzed the 128 slice spiral CT angiography (CTA) data of 222 cases with cerebrovascular disease from 2013 January to 2014 June retrospectively. Intracranial vascular abnormalities were divided into normal group (94 cases), cerebral infarction group (72 cases) and aneurysm group (56 cases), three groups of ratio analysis patients with Willis ring vessel variation, correlation analysis of the occurrence and development of cerebral vascular diseases. Results The components of the circle of Willis vessel had many variations, the variation rate was 84.68%, see ACA-A1, PCA-P1, ACoA, PCoA mutation, A1 mutation in cerebral infarction group were higher than the normal group (P<0.05); aneurysm group ACoA showed significant differences between the rate and A1 rate of mutation, the display rate of PCoA P1 mutation rate and FTP incidence and cerebral infarction group and the normal group (P<0.05); normal group Willis mutation rate is 80.85%, aneurysm group variation rate was 86.11% and the cerebral infarction group variation rate was 89.29%, no significant differences between groups (P>0.05). Conclusion The variation of circle of Willis has close relationship with cerebral infarction and aneurysm, multi slice spiral CT 3D imaging reconstruction can clear display the forms of Willis cirle, which helps to make clear the cerebrovascular pathological mechanism and improve the accuracy rate of diagnosis.