Objective To investigate the application of double-low dose in CT angiography (CTA) of patients with acute aortic syndrome (AAS). Methods A total of 130 patients with AAS undergoing CTA in the hospital from May 2014 to May 2017 were selected as the subjects. According to the scanning program, they were divided into group A (treated with voltage 80-100kV and iohexol 300mgI/ml, 71 cases) and group B (treated with voltage 120kV and iohexol 370mgI/ml, 59 cases), and the other scanning parameters were the same in the two groups. The CTA image noise value, contrast noise ratio (CNR), subjective score of image quality, average CT value of each aorta, effective radiation dose (ED) and intake of contrast agent iodine in the two groups were recorded. Results There was no significant difference between the two groups in CTA image noise value, CNR, subjective score of image quality and the average CT values of aortic root, common iliac artery, ascending aorta, descending aorta and abdominal aorta (P>0.05). The ED and intake of contrast iodine in group A were significantly lower than those in group B (P<0.05). Conclusion The application of double-low dose technique in aortic CTA can not only obtain satisfactory image quality and CT value of target blood vessels, but also reduce the radiation dose and intake of contrast iodine.