The most common route of administration for in vivo anticoagulation of heparin is subcutaneous injection, either through the abdominal wall or through an intravenous pump, which is suitable for patients with acute myocardial infarction and can also be used during resuscitation thrombolysis. Heparin is prone to complications, especially during long-term use, and is prone to thrombocytopenia, which can also induce bleeding events. For patients with lower extremity deep vein thrombosis, pulmonary artery embolism, and coronary artery disease, heparin is suitable for anticoagulation therapy. During the treatment with heparin, the changes of the five coagulation items should be monitored, and if the drug can be stopped, it should be replaced by oral drugs, mainly warfarin or rivaroxaban. Long-term use of the drug requires regular monitoring of the blood routine and changes in liver and kidney function indicators, because the drug can also occur liver and kidney adverse reactions, such as increased transaminases.