Hypertension is a common chronic disease. It is a clinical syndrome with functional or organic damage of heart, brain, kidney and other organs. The Renin-angiotensin-aldosterone System (RAAS) is the most important blood pressure regulation system in the human body and is composed of a series of hormones and corresponding enzymes. This system can regulate the body's blood pressure, water and electrolyte balance, maintain a constant internal environment, and promote the growth and metabolism of cardiac muscle and vascular smooth muscle. At present, it has become an important index for the classification diagnosis, treatment and research of primary and secondary hypertension, and has great significance for the diagnosis, treatment and pathogenesis of the disease.