Low blood pressure refers to the usual measurement of blood pressure below the normal state and is mainly seen in the following cases. First, physiological hypotension, the patient’s blood pressure is lower than normal, and the heart structure and function are normal when the cardiac ultrasound is done, and there are no uncomfortable symptoms. Generally there is no effect on the human body, do not worry excessively. Second, hypertensive patients taking excessive antihypertensive drugs, mostly occur during the period when the patient with hypertension first starts taking antihypertensive drugs. During this period to do blood pressure monitoring, such as the discovery of low blood pressure, drug dose is large, timely reduction of drug dose, help to change the state of low blood pressure. Third, the heart itself, the most common is hypotension after acute myocardial infarction. Regardless of previous cardiovascular diseases such as coronary heart disease, once unexplained hypotension is found, attention must be paid to early examination of electrocardiogram and cardiac ultrasound, paying attention to the exclusion of myocardial infarction. In addition, young people with chest tightness, panic and hypotension after a cold should pay attention to exclude myocarditis, especially fulminant myocarditis.