Most beta-blockers inhibit myocardial contractility and reduce myocardial blood output, thereby lowering blood pressure. Initial administration of beta-blockers decreases cardiac output and is accompanied by an increase in peripheral vascular resistance, which does not lower blood pressure significantly. The blood pressure decreases significantly only after prolonged administration, and the peripheral vascular resistance decreases, while the cardiac blood volume is still significantly reduced. In addition, the antihypertensive mechanism of these drugs is also related to blocking central beta receptors and inhibiting the release of some substances that can raise blood pressure. Thus, it seems that the antihypertensive mechanism is achieved by the combined action of several mechanisms. Therefore, β-blockers can be suitable for three kinds of hypertensive patients. (1) Combined coronary heart disease: such as hypertension with exertional angina pectoris patients, β-blockers can both prevent and treat hypertension and angina pectoris. Especially in patients with myocardial infarction, the application of β-blockers can prevent reinfarction and improve the prognosis of patients. (2) Hypertension in young people: because of rapid heart rate and high cardiac output, the use of drugs can significantly reduce blood pressure and improve symptoms. (3) Hypertensive patients with increased diastolic blood pressure: Clinical studies have shown that the reduction of diastolic blood pressure is more obvious than that of systolic blood pressure, so it is suitable for treating hypertensive patients with high diastolic blood pressure alone or combining with other types of antihypertensive drugs to treat hypertensive patients with both systolic and diastolic blood pressure. Since beta-blockers have the effect of slowing down the heart rate, the heart rate should be closely monitored to ensure that the heart rate is greater than 60 beats per minute, and the dose should be started from a small dose and gradually increased to achieve the purpose of smooth blood pressure lowering. In addition, it is also suitable for hypertensive patients who need vasodilators or certain calcium antagonists (nifedipine).