Objective To study the diagnostic value of CT scan and its postprocessing techniques in aortic dissection aneurysm (AD). Methods 56 cases of AD patients who were admitted in our hospital between March 2013 and December 2015 were selected as the study objects. All of them underwent multi-slice spiral CT (MSCT) examination. Meanwhile, multiple planar reconstruction (MPR), volume rendering (VR) and other different image postprocessing techniques were used for three-dimensional reconstruction. AD type, true and false lumens, size and number of intimal initial rupture were observed and recorded. The detection rates of different image postprocessing techniques in AD rupture were compared. Results Debakey typing: there were type I 12 cases, type II 7 cases and type III 37 cases. In 56 patients with AD, the density of true lumen significantly larger than that of the false one accounted for 92.9%; Diameter of false lumen significantly larger than that of the true lumen accounted for 94.6%; Clear display of rupture accounted for 87.5%. The display rates of MPR for rupture, true and false lumens and intimal flap were 92.8%, 96.4% and 100.0% respectively; The display rates of CPR for rupture, true and false lumens and intimal flap were 96.4%, 98.2% and 100.0% respectively; MIP did not display AD rupture and intimal flap while the display rate for true and false lumens was 76.8%. The display rates of VR for rupture, true and false lumens and intimal flap were 23.2%, 100.0% and 98.2% respectively. The display rates of MPR and CPR were significantly higher than that of VR (P<0.05), and the display rates for true and false lumens were significantly higher than that of MIP (P<0.05). Conclusion MSCT is of great value in diagnosis of AD. Besides, MPR and CPR have more advantages in displaying AD rupture, true and false lumens and intimal flap, compared with other image postprocessing techniques.