The correct steps of single-person CPR are: rapid judgment, initiation of EMS, chest compressions, and artificially assisted breathing. 1. Rapid judgment: When the patient suddenly collapses or loses consciousness, the patient’s condition should be judged immediately, using the way of light beat and heavy call to judge whether consciousness is awake, observing whether the chest is undulating to judge whether there is independent breathing, listening to the heart sound or touching the aorta to judge whether there is a heartbeat, the judgment time should be less than 10 seconds. 2. Activate EMS: When it is judged as respiratory and cardiac arrest, EMS should be activated immediately, call the emergency telephone and carry out rescue, lay the patient supine on the hard ground or on a board bed, with the limbs flat and straight. 3. Thoracic cardiac compression: fully expose the chest, fold both hands, place the heel of the palm on the line between the center of the sternum and the two nipples, straighten the upper limbs, and use the gravity of the body to press downward with the depth of 5~6 cm, the frequency of 100~120 times/min, and press 30 times. 4. Artificially assisted respiration: open the airway, tilt the head and lift the jaw. Remove denture and oral foreign objects to prevent aspiration. Use mouth-to-mouth, mouth-to-nose, or balloon mask for artificial respiration for 2 times, artificial assisted respiration can be seen in the chest rise and fall. Perform continuous chest compressions and artificial respiration at a ratio of 30:2. If CPR needs to be discontinued, make a vital sign determination, which should take less than 10 seconds, and if no vital signs are present, CPR needs to be continued.