Diuretics are commonly used in the treatment of hypertension. As the name implies, the effect of lowering blood pressure is achieved through diuretic effect. The initial antihypertensive mechanism of diuretics is sodium excretion and diuresis, which reduces sodium and water in the body, resulting in a decrease in blood volume and lower blood pressure. The long-term use of diuretics, when blood volume and cardiac output have gradually returned to normal, blood pressure can still continue to decrease, the possible mechanisms are as follows: 1. Decrease the responsiveness of vascular smooth muscle to vasoconstrictor substances such as norepinephrine; 3. Induce the production of vasodilator substances in the arterial wall, such as kinins and prostaglandins. Commonly used diuretics are divided into high potency diuretics, i.e. medullary collaterals (furosemide, diuretic acid), medium potency diuretics (dihydrochlorothiazide, chlorothiazide), and low potency diuretics (ambrisentin, aminoglutethimide) according to the strength of their antihypertensive effect, and all low potency diuretics have potassium conservation effects. Diuretics can be used alone to treat grade 1.2 hypertension and over the years have often been combined with other antihypertensive agents to treat moderate and severe hypertension. In the treatment of hypertension, thiazide diuretics are particularly suitable for patients with grade 1.2 (mild or moderate) hypertension, elderly hypertension, simple systolic hypertension and hypertension combined with congestive heart failure; medullary diuretics are suitable for patients with hypertension combined with renal insufficiency and congestive heart failure. These diuretics are not used as first-line drugs for mild hypertension, but for hypertensive patients with hypertensive crisis and hypertension with chronic renal insufficiency, because they do not reduce renal blood flow and have a strong natriuretic effect. From this point of view, it is beneficial for patients with renal insufficiency. Diuretics of the aldosterone antagonist class are indicated for patients with hypertension combined with congestive heart failure or after myocardial infarction. In addition, elderly patients with hypertension are mostly volumetric hypertension and the addition of small doses of diuretics can reduce water and sodium retention in the body to play a good antihypertensive effect and small doses of diuretics have little effect on blood glucose, blood lipids and potassium. The biggest advantage of diuretics is their low cost. However, its use is often neglected in clinical practice. For hypertensive patients with a clear diagnosis (excluding secondary hypertension), who have been regularly taking two types of antihypertensive drugs other than diuretics, if their blood pressure is still not under control (office blood pressure is greater than 140/90 mmHg or 24-hour ambulatory blood pressure is greater than 130/80 mmHg), the third antihypertensive drug should be added with diuretics starting from a small dose and gradually increasing the dose to mostly control blood pressure better. In recent years, whether anti-hypertensive drugs can improve the prognosis of patients is the focus of attention. A number of large clinical trials in Europe and the United States have confirmed that the application of low-dose thiazide diuretics significantly reduces the incidence of stroke and coronary heart disease, reverses left ventricular hypertrophy, and has no adverse effects on sugar, fat, and electrolyte metabolism than high-dose. 14 large-scale clinical trials have found that low-dose diuretics reduce the incidence of cerebrovascular accidents by 42%. In addition, it is noteworthy that the latest studies further affirm the first-line antihypertensive status of diuretics, which are indispensable in combination medications, including in diabetic patients. These large international studies all show that diuretics can reduce cardiovascular disease and improve people’s quality of life.