Aortic aneurysms are the major disease processes affecting the aorta and becoming a relatively common cause of death because of rupture or dissection. The most common location for aneurysms is the infrarenal abdominal aorta, followed by the ascending thoracic aorta. Unlike coronary heart disease, the incidence of abdominal aortic aneurysm (AAA) in the United States and Europe has been increasing, and this increase may not be due to higher levels of screening for this condition alone. Aortic diameter is central to the diagnosis of aortic aneurysm. Furthermore, it was demonstrated that non-AAA patients with an enlarged diameter of the infrarenal aortic diameter are also at high risk for all-cause mortality. And aortic root dimension was associated with several coronary artery disease (CHD) risk factors and measures of subclinical disease and was predictive of incident congestive heart failure (CHF), stroke, cardiovascular disease (CVD) mortality, and all-cause mortality, but not of incident MI. Up to now, there are limited studies on the epidemiology of aortic diameter, especially in Chinese population.