Chronic disseminated intravascular coagulation (DIC) is a rare but devastating complication of aortic aneurysm (AA). This study investigated the clinical manifestations, laboratory findings, and treatment of patients with AA-associated chronic DIC (AA-DIC) and explored the mechanisms, duration, and therapeutic response of AA-DIC. We retrospectively reviewed the medical records of 235 AA patients admitted at the Peking Union Medical College Hospital between September 2009 and January 2015. The patients were classified as those with DIC (AA-DIC) and those without DIC (non-DIC). The AA-DIC group showed a significantly higher proportion of female patients and a significantly longer AA disease course than the non-DIC group did. The AA-DIC patients presented mural thrombi, dissecting aneurysms, a family history of AA, and diabetes significantly more frequently than the non-DIC patients did. Furthermore, multiple regression analyses revealed that sex, mural thrombus, aneurysm type, diabetes, and stent surgery are possible independent risk factors for AA-DIC patients. Fifty-two (22.1%) patients presented AA-DIC. Among these patients, 43 had non-typical DIC and 9 had typical DIC; the mortality rate of the latter was 22.2%. The mean age of the patients with typical DIC was significantly higher than of that of patients with non-typical DIC. The non-typical DIC patients also presented abnormal coagulation disorders of varying degrees. Furthermore, heparin or low-molecular-weight heparin improved the clinical symptoms and laboratory parameters in patients with AA and typical DIC. Thus, chronic DIC should be considered in patients with AA.