The International Society of Pain (ISAP) defines pain as an unpleasant sensory and emotional experience caused by an actual or potential tissue injury. Therefore, pain itself is a personal subjective experience, which means that no one other than the person himself or herself can clearly know the state of pain of others, including the nature and extent of pain. Patients with cancer pain are often under the double psychological pressure of cancer and pain, worrying about the development and treatment of cancer and suffering from pain at the same time. Under the multiple psychological pressures for a long time, most of the cancer pain patients will have psychological problems. With the duration of pain and the strengthening of pain level, the psychological problems of patients become more prominent. The most common psychological problems include anxiety, depression and emotion, etc. If family members cannot understand them, they often think that the patient exaggerates the pain on purpose. If one can understand that pain is a subjective experience, then it is understandable that the pain confided by the cancer pain patient should be the pain he is currently experiencing. In clinical oncology treatment, we often encounter cancer patients saying “I am so happy to die suddenly like a heart attack patient” and “Can the doctor end my life journey earlier” and other words with light-hearted tendency. Severe pain is one of the main factors leading to patients’ suicidal tendency, and psychotherapy can adjust patients’ psychological disorder, which helps to relieve pain and improve patients’ quality of life. Therefore, in cancer pain treatment, it is important to pay attention to patients’ psychological problems, especially for patients with severe pain, and psychotherapy while giving analgesia will reduce the influence of psychological problems on pain and significantly improve the analgesic effect and patients’ quality of life. In addition to general psychotherapy, cognitive therapy and behavioral therapy under the guidance of hospital doctors, family psychotherapy of patients’ family members is also very important. Since family members live together day and night and have a special relationship, they are very familiar and understand each other, it is difficult to play a therapeutic role when relying only on methods such as reasoning in family psychological support. In the process of psychological support, it is necessary to pay attention to the impression of emotion and behavior, and solve the existing problems with understanding, care and frankness. Some patients say that one hour of pleasant communication with their family members has a better effect on pain relief than taking morphine, which shows the important role of family psychological support.