Objective To explore the clinical value of multi-slice spiral CT angiography (MSCTA) and its three-dimensional reconstruction in the diagnosis of intracranial aneurysms(IA). Methods The MSCTA and DSA images of 200 patients with IA which diagnosed by surgery from November 2016 to April 2018 in our hospital were analyzed retrospectively. Three-dimensional post-processing all imagings , and the detection rate of IA was compared between MSCTA and DSA, and the maximal tumor diameter, the tumor neck width, the total examination time and the examination cost were compared between the two examination methods. Results A total of 214 aneurysms were detected in 200 cases, and 205 (95.79%) cases were detected by MSCTA before surgery and 9 (4.21%) cases were missed diagnosis. A total of 210 (98.13%) were detected by DSA and 4 (1.87%) were missed diagnosis. There was no statistically significant difference in the detection rate of aneurysms between the two examination methods (P>0.05). There was no significant difference in the maximal tumor diameter and tumor neck width between MSCTA and DSA (P>0.05). The examination time and examination cost of MSCTA were significantly less than those of DSA (P<0.05). Conclusion MSCTA and the three-dimensional reconstruction can display the location, size and surrounding spatial relationship of aneurysm clearly. The detection rate of IA is comparable to that of DSA, and it has the advantages of non-invasiveness, rapidity, and low examination cost. Therefore it can be used as the first choice for IA examination.