Absent in melanoma 2 (AIM2) is a member of the PYHIN (pyrin and HIN domain-containing protein) family. It senses double-stranded DNA (dsDNA) and assembles the AIM2 inflammasome. Activation of AIM2 inflammasome causes cell pyroptosis as well as the release of interleukin (IL)-1β and IL-18, thereby leading to inflammation. The AIM2 inflammasome can become activated in atherosclerotic plaque and abdominal aortic aneurysm wall, and its activation has close links to the progression of atherosclerosis and abdominal aortic aneurysm. This review will focus on the structure and function of AIM2 and its role in atherosclerosis and abdominal aortic aneurysm.