The kidneys have three basic functions: 1, the production of urine, excretion of metabolites: the body in the process of metabolism produces a variety of waste, the vast majority of waste through the glomerular blood filtration, renal tubular secretion, with the urine out of the body. 2.Hold the fluid balance and acid-base balance in the body: the kidney through the filtration of the glomerulus, renal tubular reabsorption and secretion function, excretion of excess water in the body, regulate the acid-base balance, maintain the stability of the internal environment. 3.Endocrine function: ①Secrete renin, prostaglandins, kinins. The blood pressure is regulated by the renin-angiotensin-aldosterone system and the kinin-bradykinin-prostaglandin system. (ii) Erythropoietin. Stimulates bone marrow hematopoiesis. (iii) Active VitD3. Regulates calcium and phosphorus metabolism. ④Many endocrine hormone degradation sites – such as insulin, gastrointestinal hormones, etc. When renal insufficiency these hormones T1/2 is significantly prolonged, thus causing metabolic disorders. ⑤ The target organs of extra-renal hormones. Such as parathyroid hormone, calcitonin, etc. can affect and regulate renal function. It can be seen that the kidney plays an important function in maintaining the stability of the body’s internal environment.