Syncope is a disorder of consciousness caused by a transient lack of blood supply to the brain due to various reasons. Patients suddenly feel dizzy, dazed, blurred vision or black eyes, weakness of limbs, which is the aura of syncope; followed by loss of consciousness, fall to the ground, within seconds to minutes will recover as usual, get up and walk, some patients can have a general feeling of weakness within half an hour. In many cases, the symptoms disappear quickly if the patient falls quickly instead of falling, does not lose consciousness, or has experience with repeated occurrences and squats in time. In syncope, the heart rate slows down or increases, blood pressure drops, the face is pale, and cold sweat may occur. Syncope basically occurs in the standing or sitting position, but if it occurs in the recumbent position, attention should be paid to the presence of cardiovascular and cerebrovascular diseases such as arrhythmia, transient ischemic attack or epilepsy. There are many causes of syncope, the common ones are: (1) autonomic dysregulation, vasodilation and contraction disorders: for example, cerebral blood supply disorders in upright hypotension can cause syncope, which is more common in people with poor physical fitness; a large amount of urination at one time or continuous coughing can reduce the amount of cardiovascular blood return and cause syncope. (2) Cardiogenic cerebral ischemia: this cause of syncope is the most serious, mostly seen in severe rapid or slow arrhythmias, cardiac arrest. It can occur in any position and can be accompanied by twitching of the limbs and incontinence when the ischemia is severe. (3) Cerebrovascular disease: This condition is mostly caused by sudden onset of brainstem hypoperfusion, which should be called transient cerebral (posterior circulation) ischemic attack because of the inability to maintain normal consciousness due to ischemia of the brainstem reticular superior activating system. In addition, syncope can also be seen in people with hypoglycemia, severe anemia and hyperventilation.