Cancer pain is characterized by long duration, obvious pain and mental and psychological abnormalities. 1. Long duration, most of the cancer pains start to appear from the middle stage and last throughout the whole course of the disease, and they are aggravated, evolving from grade one pain to grade three pain, and the pain time can reach several years. 2. Obvious pain, most of the cancer pains are very obvious and intense, and some late-stage patients can hardly improve with pain-relieving drugs and need to increase the dose of pain-relieving drugs. 3. Accompanied by mental and psychological abnormality, after being stimulated by pain for a long time, the patient’s psychology and spirit will have many abnormal manifestations, which will lead to the emergence of anxiety and depression.