Cardiac arrest can lead to collapse of the heart pumping function, circulation collapse, no blood ejection from the heart, no blood perfusion to other organs and organs, and direct threat to life. In the event of cardiac arrest, if you find someone on the ground, you should first go and call out loudly, and if there is no response, you should tap both shoulders and call next to the patient’s ear bilaterally, and if there is still no response, you should call 120 to activate the emergency response system. If professionally trained, the patient’s aorta should be touched at this point and breathing should be observed. If it is the general public, without relevant training, as soon as the patient’s breathing is found to have stopped and the aortic pulsation is mostly absent, chest compressions should be started immediately at this time. At the junction of the middle and lower 1/3 of the sternum, the hands should be crossed and overlapped, the fingers should be interlocked, and the palm root should be pressed vertically, requiring a compression rate of not less than 100-120 times per minute and a compression depth of not less than 5-6 cm, and five cycles of compressions, for about 2 minutes, when the physical strength may not be sufficient, another compressionist should be replaced at this time, and wait for the arrival of 120 emergency personnel, and there should be 2 out of 30 compressions. Ventilation. First of all, there are two things that must be done before ventilation, if the patient has secretions from the mouth and nose and dentures, they should be removed and the secretions from the mouth and nose should be cleared, and the airway should be opened using the head-up chin-lift method. Effective artificial respiration can only be achieved with one second of ventilation at a time if the airway is fully open, hence the term 30:2 compression to ventilation ratio. If the patient is in cardiac arrest due to a traumatic condition and the presence of cervical spine injury cannot be ruled out, the maneuver to open the airway should become a push-up jaw method to avoid re-injury to the cervical spine.