The working principle of the kidney is to excrete metabolites, regulate water, electrolyte and acid-base balance, maintain the stability of the body’s internal environment and endocrine function. The main function of the kidneys is to produce urine, remove waste products from the body through urine, regulate the acid-base balance of the body, and also have certain endocrine functions, secretion of renin, erythropoietin, etc., which is conducive to the regulation of blood pressure, and can be used to promote the growth of bones, stimulate the bone marrow hematopoiesis, and help the bones to maintain the stability of the calcium-phosphorus metabolism. Kidneys are composed of renal units, which include glomeruli and tubules. Glomeruli mainly play the function of filtration, while tubules mainly play the role of reabsorption, reabsorbing useful components into the blood, while harmful components are excreted in urine. If kidney disease is detected, it is recommended to consult the nephrology department of a regular hospital and follow the doctor’s instructions to complete the examination and definitive diagnosis and treatment.