The use of epinephrine in resuscitation depends on the specific circumstances of the resuscitation. There are many clinical scenarios in which epinephrine is often used, including sudden cardiac death or sudden death due to other causes, when performing basic life support and advanced life support, and anaphylactic shock, etc. Different usage is required according to different situations. First, sudden death resuscitation epinephrine as a basic drug for cardiopulmonary resuscitation, has a history of more than 40 years, the use is intravenous injection, every 3-5 minutes can be repeated injection. Current research suggests that epinephrine can enhance myocardial contractility, increase coronary blood flow and cerebral blood flow, increase myocardial autoregulation, and increase the possibility of ventricular fibrillation transient during electrical defibrillation. To date, epinephrine remains the first-line agent for cardiopulmonary resuscitation and can be applied in ventricular fibrillation where electric shock is ineffective, where there is no chronic electrical activity in the heart, or in cardiac arrest. Historically, the use of epinephrine intracardiac injection has occurred, but intracardiac injection may increase the risk of coronary injury, pericardial tamponade, and pneumothorax, as well as delay the initiation of cardiac compressions and pulmonary ventilation, and is therefore rarely used today. Second, anaphylaxis rescue at this time the use of epinephrine is generally intramuscular injection, about the injection site there are many controversies in clinical research. At present, it is believed that if the anaphylaxis is caused by drugs, it is best to inject at the site of the original injection of drugs to slow down the absorption of drugs. For other causes of anaphylaxis, such as food, some recommend injection in the outer thigh for the fastest onset of action, but it is still an intramuscular injection. When epinephrine is injected subcutaneously, both the absorption and the time to reach the maximum plasma concentration are long, which can delay the resuscitation time of anaphylaxis and affect the resuscitation effect, so it is no longer used. If the anaphylaxis does not improve after the first injection or the condition is serious, additional injections can be continued. Third, anaphylaxis combined with cardiac arrest when epinephrine is generally given intravenous injection, every 3-5 minutes.