Abstract: Objective: To evaluate the clinical value of 64 row helical CT angiography(CTA) in the diagnosis of aortic dissection (AD). Methods: The 64 row helical CTA data of 52 patients with AD were retrospectively analyzed. The images were scanned with rapid capacity enhancement by intelligent tracking technology， the original data were post-processed with multi-planar econstruction，curved planar reconstruction，maximum intensity projection，volume reconstruction and virtual endoscopy. R sults: During 52 patients with AD， type Stanford A in 12 cases and type Stanford B in 40 cases were found. All cases had the true false lumen and intimal flap.Seventy-six branch arteries were involved， crevasse and recrevasse in 98 sites were showed. The mean CT value of true lumen was higher than that of false lumen in arterial phase. Conclusions: The 64 row helical CTA has high value in diagnosing AD，which is exact and quick， can provide important information for surgery. It can be used as the preferred imaging examination in diagnosing AD.