Hypertension is a systemic disease characterized by elevated arterial pressure in the body circulation and caused by the interaction of polygenic genetic, environmental and multiple risk factors. It can be divided into primary hypertension and secondary hypertension. In the early stages of hypertension, there are often no specific symptoms, except for a mild increase in blood pressure, but only dizziness when exertion, stress, mental and emotional changes, swelling and pain in the temples on both sides, and easy fatigue. In some cases, elevated blood pressure is detected only when there is a nosebleed or conjunctival bleeding. In a few cases, elevated blood pressure is not detected until there is major target organ damage such as heart failure or cerebrovascular accident. Blood pressure measurement is the primary means of diagnosing hypertension and assessing its severity. The criteria for measuring hypertension in the clinic are >140/90 mmHg, 135/85 mmHg for self-measurement, 24-hour average ambulatory blood pressure <130/80 mmHg, daytime average 135/80 mmHg, and nighttime average <125/75 mmHg.