When cardiac arrest occurs, it is usually impossible to save yourself and you should seek prompt intervention when you have underlying heart disease or feel that your heart is not right. Sudden cardiac arrest is the direct cause of sudden cardiac death, a state in which the ejection function of the heart suddenly stops, which in turn leads to interruption of blood circulation throughout the body, apnea and loss of consciousness. 1. Recognize cardiac arrest: Judge the patient’s reaction, check the respiratory pulse to confirm cardiac arrest and immediately start primary cardiopulmonary resuscitation (CPR). 2. Call for help: It is necessary to find a way to notify and activate the emergency medical system without delaying the implementation of cardiopulmonary resuscitation, and to search for and use an automated external defibrillator (AED) when available. 3. Primary CPR: This is basic life activity support and should be performed immediately when cardiac arrest is recognized. Resuscitation measures include manual chest compressions (C), opening the airway (A) and artificial respiration (B), of which manual chest compressions are the most important and the procedure is CAB. 4. Advanced cardiopulmonary resuscitation: refers to the further application of some auxiliary equipment and special techniques to establish more effective ventilation and blood circulation on the basis of basic life support. Including endotracheal intubation to establish ventilation, defibrillation to restore cardiac rhythm, intravenous drugs and other measures. Sudden cardiac arrest often occurs suddenly, and patients usually have no way to save themselves; at the same time, the survival rate of sudden cardiac arrest is very low. Therefore, it is important to prevent sudden cardiac arrest and sudden cardiac death. Regular medical checkups are recommended, as well as aggressive treatment of underlying heart conditions to prevent sudden cardiac arrest.