The carotid artery is the lifeline of the brain, supplying a constant supply of energy to the brain, so it is important to protect it during the day. If plaque forms on the walls of the carotid artery, the carotid artery will gradually narrow or even become blocked, which is very dangerous. There are many people around us who have found plaque in the carotid artery wall during carotid ultrasonography, which makes them panic. How many mm of carotid plaque is considered serious? Under normal circumstances, the normal thickness of carotid artery intima should be less than 1mm, between 1-1.2mm indicates intimal thickening, while if it is greater than 1.2mm, there is plaque formation. Carotid artery plaque greater than 1.2mm is considered to be more serious, at this time the plaque will cause the lumen to narrow, affecting the normal blood flow, if not timely treatment and control, plaque enlargement will lead to cerebral ischemia symptoms. In clinical practice, carotid plaque can be divided into hard plaque and soft plaque, but soft plaque is more dangerous because it is very unstable and may rupture and fall off at any time. Once it ruptures and falls off, the plaque will move with the blood circulation and lead to blockage of other blood vessels, resulting in brain embolism, stroke, paralysis or even coma. Carotid plaque is a serious problem, so treatment should not be careless. Carotid endarterectomy can remove the diseased carotid plaque under the microscope, eliminate the source of emboli, restore the smoothness of the inner wall and the normal size of the inner diameter of the carotid artery, greatly improve the blood supply, and effectively prevent the occurrence of cerebral infarction.