The renin-angiotensin-aldosterone system (RAAS) is an important endocrine system that regulates blood pressure in the body and consists of a series of hormones and corresponding enzymes that play an important role in the regulation of water and electrolyte balance as well as blood volume, vascular tone and blood pressure. As a protein hydrolase, mainly synthesized and excreted by the proximal glomerular cells, renin can hydrolyze blood a2 globulin, i.e., angiotensinogen, into 10-peptide and physiologically inactive angiotensin I, which is converted into 8-peptide angiotensin II under the action of angiotensin-converting enzyme, Ang II is one of the strongest known vasoconstrictive active substances. Angiotensin acts on vascular smooth muscle to constrict micro-arteries and increase arterial blood pressure, and promotes the secretion of aldosterone, which has the effect of retaining water and sodium and increasing blood volume, from the adrenal glomerular band to constrict blood vessels and increase blood pressure. Under normal conditions, renin, angiotensin, and aldosterone are in dynamic balance, feeding back and restraining each other. In pathological conditions, RAAS can be an important mechanism for the development of hypertension.