Utilizing modern technology, the toxins and water in the human body are excreted through the machine to achieve the purpose of artificial kidney, which is called blood purification, including hemoperfusion, hemofiltration, bedside hemofiltration and so on. It is mainly applied to chronic renal insufficiency, acute renal insufficiency, drug intoxication and other diseases. It is commonly used for patients with chronic renal failure, due to the problems of the kidneys leading to the problems of water metabolism, toxin metabolism, and electrolyte metabolism, and the blood purification should be achieved by the principle of blood convection and dispersion at this time.