Marfan syndrome (MFS) is a hereditary connective tissue disorder characterized by abnormalities in the bones, eyes, and cardiovascular system, especially dissection and rupture of the ascending aorta, which usually lead to sudden death. This article describes the case of a 55-year-old male patient with MFS who was diagnosed with chronic type A aortic dissection after postoperative computed tomography angiography. The imaging manifestations demonstrated the degree of aortic dissection, thrombus formation in the true and false lumens, or pericardial effusion, and hence, provided reliable information on the course and prognosis of the disease. Therefore, under non-invasive conditions, clinicians should be immediately assisted in making a diagnosis, and medical and surgical treatment should be administered as soon as possible to improve the survival rate of MFS patients.