Heparin calcium has anticoagulant effect and is mainly used clinically to prevent the formation of thrombus and to prevent the further expansion of thrombus already formed, mainly in the following cases: i. Prophylactic use in surgery with the risk of thromboembolism formation, such as hip and knee surgery in orthopedics. Second, for the treatment of formed deep vein thrombosis, the method used is subcutaneous injection. It can be used for the anticoagulation treatment of unstable angina pectoris and the acute phase of myocardial infarction, and is usually used together with aspirin or clopidogrel, which have anti-platelet aggregation effect in clinical practice. Four, in hemodialysis to prevent the formation of blood clots in the extracorporeal circulation, heparin calcium can induce thrombocytopenia, so in the use of the process of dynamic monitoring of platelet counts, once the platelet count decreased by more than 30% than the base value, the need to discontinue the use of heparin calcium.