Objective To evaluate the value of 16slice spiral computed tomography (SCT) and its threedimensional reconstruction in diagnosis of aortic dissection (AD). Methods Fortyfive cases with AD underwent 16slice SCT, performed with unenhanced, contrastenhanced scanning and threedimensional reconstructions. Emphasis was placed on the true and false lumen, intimal flap, the entry and reentry tear and the involvement of branches of AD. Eleven cases were confimed by operation. Results True and false lumen and intimal flap of AD could be shown in all 45 cases (100%), the entry and reentry tears were revealed in 44 cases (97.8%) and 33 cases (73.3%), respectively. The right common iliac arteries were most easily involved by AD, 21 cases (46.7%). The thrombi in false lumen were shown in 29 cases (64.4%). Compared with surgery, the location and size of initial entry sites of 11 cases were consistent with the former. Conclusion 16slice SCT can exactly and completely diagnose AD, and provide detailed imaging information for clinical therapy. It’s very important for the selection of treatment methods and the observation of curative effect of patients.