In 2017, the American Heart Association published a new version of the American hypertension guidelines, which re-established the range of hypertension judgment, adjusting the previous criteria for hypertension (systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg) downward to (systolic blood pressure ≥ 130 mmHg and/or diastolic blood pressure ≥ 80 mmHg). However, the classification of hypertension currently applied in China is still divided into three levels according to the original criteria. The current diagnostic criteria for hypertension in China are: if the blood pressure is measured once a day for three days without anti-hypertensive drugs, respectively, and if the systolic blood pressure is ≥ 140 mmHg and/or diastolic blood pressure is ≥ 90 mmHg, hypertension can be diagnosed. Patients with a previous history of hypertension who had received regular blood pressure-lowering treatment were diagnosed with hypertension despite a blood pressure <140/90 mmHg. Hypertension was further classified into three levels according to the level of elevated blood pressure. Class I hypertension (mild) was defined as systolic blood pressure 140-159 mmHg and diastolic blood pressure 90-99 mmHg; Class II hypertension (moderate) was defined as systolic blood pressure 160-179 mmHg and diastolic blood pressure 100-109 mmHg; Class III hypertension (severe) was defined as systolic blood pressure ≥180 mmHg and diastolic blood pressure ≥110 mmHg. For children, the 95% median of blood pressure values for different age groups, usually lower than adult levels, is used. The classification of hypertension can guide clinical management. In simple grade I hypertension, dietary modification and lifestyle improvement may be the first course of action, without the need for immediate drug therapy. Drug therapy is added on top of the above-mentioned diet and lifestyle treatment that has failed for six months. However, drug therapy must be initiated immediately for grade II hypertension or higher.