Syncope is a brief loss of consciousness caused by a transient lack of cerebral blood flow due to neurological reflexes, cardiac and cerebral diseases, and other etiologies. There are several types of vasodilatory disorders, mainly vasodepressive syncope and syncope due to upright hypotension. Less common are urinary syncope and cough syncope and other vasopressor syncope (simple syncope): the most common, accounting for about 58.4%, mostly seen in young and weak women. There are often triggers that can be investigated, such as pain, emotional stress, fear, hot weather, fatigue, fasting and minor surgery. Another characteristic is that it often occurs in the standing or sitting position, but rarely in the lying position. Syncope occurs with a drop in blood pressure, a slowed and weak heart rate, and a pale face with cold sweats, but recovery is quick and there are no obvious sequelae. The main cause is the vasodilation of blood vessels in the muscles of the body caused by these triggers through the vagal reflex, which causes a drop in blood pressure. Syncope due to upright hypotension (postural hypotension) occurs when the patient takes an upright position or stands for a long time, due to the accumulation of blood in the lower extremities, which reduces the amount of cardiac blood return and decreases the systolic blood pressure, resulting in a momentary lack of blood supply to the brain. This disease can be physiological, but can also be seen after taking certain drugs and systemic diseases such as diabetes, spinal cord lesions, etc.. Such patients should be immediately laid down and placed in a place with air circulation. 2, cardiogenic syncope This type of syncope is the most serious, due to reduced cardiac output or cardiac pulsation in heart disease, which can be caused by severe arrhythmias, cardiac blood displacement obstruction, myocardial ischemia, etc.. Syncope can occur suddenly in any position, usually for a few seconds to a few minutes, and may be accompanied by seizure-like convulsions, occasional incontinence, pallor, and loss of heartbeat and pulse. Once the occurrence of cardiogenic syncope, should be immediately whirling rescue, bystanders immediately perform cardiac massage. 3, cerebral syncope due to cerebrovascular circulation disorders, resulting in transient widespread cerebral blood supply deficiency. The most common is transient cerebral ischemic attack, which is caused by widespread microemboli. Frequent seizures often indicate that a larger cerebral sclerosis will Lei. Risk factors such as hypertension, hyperlipidemia and diabetes mellitus should be actively treated, and aspirin enteric solution tablets should be used to anti-platelet aggregation. 4, blood component abnormalities Hypoglycemia, severe blood greed and hyperventilation syndrome caused. In conclusion, there are many causes of syncope, vasodilatory disorders are often not dangerous, while cardiogenic syncope is the most dangerous. After history taking and physical examination, the doctor may also perform ECG, 24-hour ambulatory ECG, echocardiogram, cranial CT, cranial MRI, blood glucose, and routine blood tests depending on the situation. We have also encountered cases of fainting due to acute blood loss from upper gastrointestinal hemorrhage or ectopic pregnancy who came to the hospital for emergency care.