The normal range of blood pressure is age dependent. The standard normal range of blood pressure for adults applies to men and women over the age of 18 years, while children use the 95th percentile of blood pressure values for different age groups, which are usually lower than adult levels. Blood pressure levels are continuously normally distributed in the population, and there is no clear boundary between normotension and elevated blood pressure; the criteria for hypertension are defined based on clinical and epidemiological data. Blood pressure was measured once a day, respectively, for three days without the use of antihypertensive drugs. Hypertension was diagnosed if the systolic blood pressure was ≥140 mmHg and/or the diastolic blood pressure was ≥90 mmHg. Patients with a previous history of hypertension who have received regular antihypertensive treatment and whose blood pressure is <140/90 mmHg are still diagnosed with hypertension. Hypertension can be classified into three levels. Grade I hypertension (mild) is systolic blood pressure 140~159mmHg and diastolic blood pressure 90~99mmHg; Grade II hypertension (moderate) is systolic blood pressure 160~179mmHg and diastolic blood pressure 100~109mmHg; Grade III hypertension (severe) is systolic blood pressure ≥180mmHg and diastolic blood pressure ≥110mmHg. The ideal blood pressure is systolic blood pressure <120mmHg and diastolic blood pressure <80mmHg; normal blood pressure systolic blood pressure <130mmHg and diastolic blood pressure <85mmHg; normal high value is systolic blood pressure 130~139mmHg and diastolic blood pressure 85~89mmHg. between normal blood pressure and elevated blood pressure is defined as normal high value. When the blood pressure level is at the high normal value, it predicts that the cardiovascular risk will be elevated.