Metoprolol has many effects, and its mechanism mainly plays many roles by antagonizing sympathetic excitation. Specifically, firstly, it has the effect of lowering blood pressure, especially in patients with sympathetic excitation. Second, metoprolol can be used in the treatment of coronary heart disease, as a member of the secondary prevention of coronary heart disease, can play a very important role, but also can reduce myocardial oxygen consumption, improve the symptoms of ischemia in patients with coronary heart disease. Thirdly, metoprolol can be used for anti-arrhythmic treatment, which has a certain effect on supraventricular and ventricular arrhythmias, and can also slow down the ventricular rate. Fourth, metoprolol can be used to treat heart failure, the sympathetic nerve of heart failure patients is excited, metoprolol as an antisympathetic very important link, can improve the prognosis of heart failure patients, with ACEI, ARB, aldosterone receptor blocker to form a golden triangle, to improve the prognosis of a treatment.