Objective To investigate the differences in the accuracy of cardiac spiral CT angiography (CTA) in the differential diagnosis of aortic dissection (AD) and aortic intramural hematoma (IMH). Methods 58 patients with AD confirmed by digital subtraction angiography (DSA) who were treated in our hospital between October 2011 and May 2015 were selected as study subjects. All the patients underwent DSA and cardiac CTA examination. The results of DSA were taken as the golden standard to evaluate the accuracy of CTA in the differential diagnosis of AD and in the differential diagnosis of AD and IMH. Results The results of DSA showed that among the 58 patients diagnosed with AD, 17 cases (29.3%) were DeBakeyⅠtype, 6 cases (10.3%) DeBakey II type, 25 cases (43.1%) DeBakey Ⅲtype and 10 cases (17.2%) IMH type. The results of CTA enhanced scan differential diagnosis showed that the accuracy in differential diagnosis of AD was 96.6% (56/58) and of IMH was 80% (8/10). Conclusion Cardiac CTA enhanced scan is with advantages such as noninvasive, safe, convenient, strong operability and high accuracy of differential diagnosis, etc.. It is of relatively higher application value in the differential diagnosis of AD and IMH.