Heparin usage in thrombolysis in heart attack is administered before or after recombinant tissue-type fibrinogen activator at a dosage of 5,000 U for the first dose, followed by additional dosages for bleeding risk. Percutaneous coronary intervention is preferred in infarction, and pharmacologic thrombolysis is an option if this treatment cannot be performed within an estimated 120 minutes. Thrombolytic drugs may include urokinase, streptokinase, and recombinant tissue-type fibrinogen activator. Heparin 5,000 U was injected before the use of recombinant tissue-type fibrinogen activator, and 12/U (kg.h) was given after the use of the drug and continued for a total of 48 hours, and then 7,500 U was injected subcutaneously every 12 hours for 3 to 5 days. Heparin is used to prevent and control thrombosis or embolic disease, also used in hemodialysis, extracorporeal circulation and other treatments, when allergic to heparin, bleeding tendency, severe liver function abnormalities are prohibited. It may cause heparin-associated thrombocytopenia, and excessive dosage may cause spontaneous bleeding. Heart attack is a clinical emergency, the choice of treatment needs to be formulated through a comprehensive assessment by a doctor, it is recommended to go to the emergency department of the hospital, chest pain center.