Modern medicine believes that the occurrence of diseases in the human body is related to the biological, psychological and social environments. Therefore, we have to consider these three aspects in order to prevent and cure diseases. Cancer in human beings is a kind of disease, and its occurrence is also related to biological factors, psychological factors and social environment factors. Spirit and emotion are specific manifestations of psychological factors. First, there is a close relationship between the good and bad of spirit and emotion and the development of cancer. “Irregularity injures the organs.” “Anger hurts the liver, joy hurts the heart, thought hurts the spleen, worry hurts the lungs, fear hurts the kidneys” and so on. Motherland medicine believes that tumors are the result of stagnation of qi and blood due to the seven emotions, injury to the spleen and stomach and other reasons. Dr. Zhu Danxi, a doctor in Yuan Dynasty of China, believed that breast rock (cancer) was caused by bad emotions such as frequent sorrow, depression and anger. Most of the cancer patients start experiencing the grief of losing their parents or relatives since childhood. The bereavement encounter develops their reticent and less talkative personality, and in adulthood they become unsociable, lack enthusiasm for work and ideals in life, and are often self-pitying and depressed. They spend their long lives often wallowing in hopelessness or loneliness. Bad spirit, emotion, poor psychological state, social stimuli is a strong cancer-promoting agent. Bad spirits and emotions have a significant cancer-promoting effect. Now when we say a person is unhealthy, it should include two aspects, on the one hand, physical illness and pain, and on the other hand, mental and emotional and psychological unhealthiness, such as long-term panic, fear, grief, anger, tension, dissatisfaction, worry, family disharmony, etc. The immune function in the body of a person with the above conditions is decreased. Decreased immune function makes people more prone to illness and cancer. It is now known that long-term mental and emotional problems can cause endocrine imbalance and lymphatic system dysfunction, which is the cause of decreased immune function. Second, how to prevent cancer from spirit and emotion? We should keep optimism, cheer up our spirit, be good at self-compassion, self-relief, work with work and leisure, maintain good relationship with colleagues, good group and family relationship, avoid being impatient, angry or depressed, which is very favorable to cancer prevention. Some people wrongly think that “cancer is incurable”, although he has been properly treated after suffering from cancer, he is still very nervous, depressed, not interested in everything, sleeps poorly and eats poorly. Like this, his immune function will be lowered, which is conducive to the recurrence or metastasis of cancer. This situation should be explained and optimism should be cultivated. In the past ten years, medical research at home and abroad has made great progress, and many early and middle-stage cancer patients can be cured; even for late-stage patients, after reasonable treatment, some of them may be cured, and some of them can reduce their pain and prolong their life. Therefore, cancer patients should set up confidence in overcoming cancer and have a good mental state. Actively cooperate with medical staff and mobilize the immune function in the body to fight against cancer. If the spirit is not uplifted, it is difficult for even the best treatment to fully show its efficacy. Poor spirit and mood can make the disease worse, and optimistic spirit can promote the improvement of the disease.