Heparin is a kind of mucopolysaccharide sulfate ester, which is so named because it was first discovered from the liver. In addition to the liver, it also exists in the gastrointestinal tract, blood vessel wall and other locations, and its main function is anticoagulation, which is a natural anticoagulant. It has been widely used in clinical practice to treat some thromboembolic diseases, acute myocardial infarction, DIC caused by severe infections, and also for some treatments such as hemodialysis and extracorporeal circulation. Heparin is usually administered by subcutaneous injection or intravenous injection, at present, common heparin and low molecular heparin are commonly used, low molecular heparin is safer than common heparin in clinical application, and has relatively high bioavailability and long half-life, in the process of clinical application, attention should also be paid to avoid the tendency of bleeding.