Accurate diagnosis is essential to achieve a good result in the treatment of aortic diseases. Preoperative three-dimensional image of thoracic aorta is important for the repair of aortic pathology. By the introduction of multi-slice computed tomography (MSCT) and multiditector-row computed tomography (MDCT), precise 3-dimensional images of vascular structure can be achieved more rapidly and easily. The aortic surgeon should apply the 3-dimensional diagnosis in the most of surgical cases because the pre-operative useful information can be achieved such as precise and accurate pathological vascular structure. In the diagnosis of 3-dimensional images, axial images and multi planar images should be evaluated at the same time to prevent the wrong diagnosis. In the diagnosis of 3-dimensional images, thrombus formation is usually ignored. We should understand that 3-dimensional images are reconstructed by the low data or axial images. Progress of 3-dimensional computed tomography (CT) diagnosis is a strong tool for the surgeon to get a better result in the treatment of aortic diseases.