1, to prevent the invasion of disease evil avoid their evil evil is an important condition leading to the occurrence of disease, so before the disease is prevented in addition to health to enhance the vitality, improve the ability to resist disease, but also pay attention to avoid the invasion of disease evil. Su Wen – Shang Gu Tian Zhen Lun said: “Avoid the evil and thieving wind at times.” It means that we should be careful to avoid the attacks of external evil. These include conforming to the four seasons, preventing the invasion of the six evil spirits, such as summer heat, autumn dryness, winter cold, etc.; avoiding epidemics and poisons, preventing tropical diseases; paying attention to the environment, preventing trauma and insect and animal injuries; hygiene, preventing pollution of the environment, water and food, etc. 2.Drug prevention Taking certain drugs beforehand can improve the immune function of the body and effectively prevent the attack of disease and evil, thus playing a role in disease prevention. This is especially meaningful in preventing the prevalence of plague. Ancient medical practitioners have accumulated many successful experiences in this regard. There is a record in “Suwen – Stabbing Method (Legacy)” that “Xiaojin Dan …… takes ten grains, and no epidemic will dry up.” The invention of human pox inoculation to prevent smallpox in the 16th century, which pioneered artificial immunity, has made great contributions to the development of immunology for future generations. In recent years, under the guidance of Chinese medicine prevention theory, the use of herbal medicine to prevent diseases has also achieved good results. For example, the prevention of influenza, avian influenza, infectious atypical pneumonia (SARS) and mumps with Panax quinquefolium and Daturian leaves, and the prevention of hepatitis with Yin Chen and Guanzhong are simple, affordable and effective.