The main methods of pain assessment are as follows: first, the numerical assessment approach. During the assessment, the physician will explain to the patient the concept of the numerical axis, that is, the scale from 0-10 representing pain-free to intolerably severe pain. The patient can select the appropriate number according to his or her current pain sensation to help the physician with the assessment. Second, the approach of facial expression assessment. During the assessment, the doctor will bring out a series of faces, ranging from a complete smiley face all the way to a very painful crying face, representing different pain levels, and the patient will choose the appropriate face. Third, the grading can be done by verbal description. When verbal description grading is carried out, it is divided into 0-3 grades, which are no pain at all to unbearable pain all the time, respectively. Fourth, a corresponding assessment tool can be adopted for comatose patients. For some special patients, such as those who are unable to communicate or completely unconscious, doctors and nurses can adopt the corresponding assessment form for pain assessment. The patient’s current pain level can be assessed by observing the patient’s facial expression, whether he or she is well rested, the size of the muscle tone, and whether there are any abnormal vocalizations.