What happens when a person suddenly becomes critically ill, seriously ill, poisoned, or injured? At this time, the first first-aider is the “bystander” at the scene, he or she can be a family member, colleague or passerby. If the “bystander” knows a little first aid knowledge, he or she should immediately call the national emergency number “120” while rescuing the patient at the scene in time. In this way, some dying patients will have a better chance of survival. When encountering a sudden stop of heartbeat and breathing, sweating, cold limbs, coma, breathing difficulties, shortness of breath, convulsions, hemoptysis, vomiting blood, a lot of blood in the stool, severe pain, all kinds of trauma, all kinds of poisoning and electrocution, drowning and other accidents should immediately call an ambulance. Ambulance is a special vehicle, fast speed, unobstructed passage, can be earlier to the hospital rescue. At the same time, there is a doctor on board and basic whirling facilities, which can be treated before reaching the hospital to prevent the development of the disease. When you call the “120” emergency number, when you say “Hello, this is the emergency center” three times, it means that the phone is connected, and you can talk when the dispatcher asks. The caller should not panic and should speak clearly and concisely. You should tell the patient’s detailed address, the patient’s name and the callback number so that you can contact them again if you can’t find them. Secondly, you should tell the patient’s condition and current status, so that the caller can be prepared and, if necessary, send a message to the destination hospital to get ready for resuscitation. After calling “120”, you should send someone to wait for the car at the agreed intersection. And prepare the necessary items, such as medical record cards, social security cards, daily necessities, etc. and bring them to the hospital. In order to facilitate the transportation of patients, the aisle of the residence should be cleared properly to make the transfer time as short as possible.