Defibrillators are mainly used to eliminate ventricular fibrillation and arrhythmia and restore sinus rhythm by shocking the patient’s heart directly or indirectly with electric current. The indications of defibrillator mainly include: 1. It is suitable for patients with cardiac arrest, 80% of cardiac arrest patients will have ventricular fibrillation, if using defibrillator for electric defibrillation, it is easier to eliminate ventricular fibrillation and restore sinus rhythm; 2. Patients with cardiac arrest, after 5 cycles of cardiopulmonary resuscitation, defibrillator can be used, early electric defibrillation can play a key role in the patient’s resuscitation.