With the rapid development of society, more and more problems have started to appear, especially people’s health problems. As a nephrologist, I have to say that more and more people are suffering from kidney disease and more and more patients are reaching the standard of dialysis. 2021, during the lecture at the Shanghai Eastern Conference, experts mentioned the basic data of hemodialysis in mainland China as of the end of December 2020, which was derived by statistics: hemodialysis patients: 692,736; new hemodialysis patients: 143,513; Total prevalence of hemodialysis: 494.9 pmp. What is hemodialysis? The kidney is an important excretory organ of the human body, with four major functions: 1. filtering to form urine and excreting metabolic wastes, the body’s intake of substances filtered through the kidney, retaining glucose, amino acids, calcium, phosphorus and other beneficial substances, and excreting urea, creatinine and some toxic substances; 2. secreting renin-angiotensin to help vasoconstriction, secreting prostaglandins and bradykinin to help vasodilation and maintain blood pressure balance; 3, Secrete erythropoietin to maintain and promote normal red blood cell metabolism; 4. Secrete 1,25-dihydroxyvitamin D3 to regulate calcium metabolism. Blood purification, is a technique that replaces the work of the kidneys and plays a part in their work. Blood purification (BP), also called hemodialysis, refers to the use of physical, chemical and biological methods to remove excess water from the body and metabolic waste, toxins, autoantibodies, immune complexes and other pathogenic substances in the blood, and maintain the body’s water, electrolyte and acid-base balance, in order to purify the blood. It includes a group of techniques with different principles and is mainly used for the treatment of kidney diseases (mainly uremic patients), but also for the treatment of poisoning, liver failure, autoimmune diseases, etc. Blood purification removes water and pathogenic substances through special membranes called Semipermeablemembrane. Semipermeable membranes have small pores of a specific size, and substances in solution that are smaller than the size of the pores can pass through the membrane (pores), while larger substances cannot. Through blood purification, metabolic waste products are removed from the body, such as: small molecule toxins uric acid, urea, creatinine, indole, etc.; medium molecule toxins: β2 microglobulin, parathyroid hormone, etc.; protein-bound toxins: phenol, retinol, etc. Only when these metabolites are well removed, the patient can maintain normal basic life activities.