Low molecular heparin is a general term for a class of heparins of lower molecular weight prepared from common hepatic depolymerization. Heparin is a widely used clinical anticoagulant that exerts its anticoagulant effect through the inhibition of thrombin and the inhibition of coagulation-active factor II. It is mainly used clinically for the prevention and treatment of venous thrombosis. Although heparin has been used in clinical practice to achieve good clinical results, it also brings many adverse effects, such as bleeding, heparin-induced thrombocytopenia, and allergic reactions. Low-molecular heparin, on the other hand, has the advantages of good absorption by injection, long half-life, high bioavailability, less side effects of bleeding, and low incidence of osteoporosis, etc. The clinical application of low molecular heparin is expanding continuously.