On a recent afternoon, we resuscitated a middle-aged patient in cardiac arrest. This patient was brought back from a university classroom in a university town by the emergency room upon notification from “120”, and the teacher who was lecturing suddenly collapsed and died suddenly. When our ambulance arrived, the students had already been doing cardiac compressions for a long time in the classroom, and the patient unfortunately passed away despite the fact that we organized multiple specialties to do all the resuscitation for more than three hours and used ventilators and temporary cardiac pacemakers. Generally speaking, most of the sudden deaths of patients with no obvious organic diseases can be resuscitated as long as they are in the ward, not to mention the fact that the patient was a middle-aged person who seemed to be very healthy. Afterwards, we analyzed the situation by understanding the scene in detail and asking the patient’s family and colleagues, and concluded that the death was most likely due to a serious arrhythmia. From time to time, we can learn from the media and from our side that Li Song, a cardiovascular disease specialist at Guangdong Provincial Hospital, died so young. Cardiac arrest refers to the sudden cessation of the heart’s effective beat and the sudden termination of pumping function due to various causes, resulting in the interruption of general circulation, respiratory arrest and loss of consciousness. It is characterized clinically by sudden loss of consciousness, twitching of the extremities, and loss of aortic pulsation, with intermittent or stopped breathing and pale or markedly cyanotic skin. It is the most serious cardiovascular emergency. Sudden human death occurs in 87.7% of cases outside the hospital, without the involvement of medical personnel in resuscitation. However, 35-40% of sudden deaths can be recovered if resuscitated in time. If the resuscitation is not timely, the patient will feel dizzy after 3 seconds of cardiac arrest, faint after 10-20 seconds, enter coma after 30 seconds, convulsions after 40 seconds, respiratory arrest after 60 seconds, urinary and fecal incontinence, brain cell death after 60 seconds, and irreversible death of the brain after 10 minutes. Therefore, the time of the start of resuscitation is the main influence on life and death! According to the study, if resuscitation is started within 4 minutes, 50% can be saved, if resuscitation is started within 4-6 minutes, 10% can be saved, but if the survival rate is more than 6 minutes, only 4% can be saved, and the possibility of survival is very low if it is more than 10 minutes. It can be seen that the start of CPR within 4 minutes is the golden time for resuscitation. In places outside the hospital, we can not just wait for medical personnel to the scene to rescue, each of us should learn self-help knowledge, learn CPR. Remember, time is life, and someone call the emergency number while giving help. Unfortunately, for this middle-aged teacher’s resuscitation, it took half an hour before our ambulance was notified to arrive at the scene. It is also very important to know how to perform standardized CPR; if it is not performed properly, not only will it not save the patient, but it will delay the condition. The middle-aged teacher above, although the students immediately also performed cardiac compressions, but is not standardized, if the rescue is properly administered, for further cardiac resuscitation to win valuable time, the patient is completely can be treated. A special reminder is to position the patient before compressions, so that the patient is lying on his back on the ground or on a solid surface. When turning the patient, do not be too violent, but keep the head and neck in line with the body coaxially turned to prevent further injury and paralysis in patients with spinal injuries. In cardiopulmonary resuscitation, the palms of both hands overlap, elbows straight, with the body’s gravity downward, compression depth of 4-5cm, downward pressure and relaxation of 50% of the time, after the pressure completely relaxed, but do not leave the chest wall, the frequency of 100 times / min; must avoid some due to compression posture, location and other errors that lead to rib fractures, fenestrated and liver rupture. The patient’s head should be turned to the side first, and any foreign bodies such as vomit and sputum should be cleared from the mouth to prevent blockage of the airway.