In our gastrointestinal tract, there are many tribes of bacteria, Bifidobacterium, Lactobacillus, Escherichia coli, Bacillus aerogenes, Bacillus cereus, Clostridium, Aspergillus, Staphylococcus, Streptococcus …… in great variety and number. According to statistics, the number of living bacteria in the human digestive tract is 10 times more than the human cells, and can be divided into about 400-500 kinds. In addition to bacteria, there will be some viruses, fungi and other microorganisms. Modern gene sequence detection studies have estimated that there are more than 1600 species of genes in the gastrointestinal tract. Under normal circumstances, the distribution, species, number and proportion of these microorganisms will have a certain pattern and maintain a dynamic balance with people and the environment. Under normal conditions, the majority of bacteria in the gastrointestinal tract are beneficial to the human body, and we call them “probiotics”, which help us digest lactose, degrade and excrete excess cholesterol; provide our body with vitamins B1, B2, B6, B12, as well as pantothenic acid, niacin, vitamin K, etc.; stimulate the development of our immune organs, and stimulate the development of our immune organs and promote their continuous evolution and improvement, which is beneficial to human health. Probiotics and our gastrointestinal mucosa together form an ecological barrier to resist and fight against various foreign pathogenic microorganisms, but under certain circumstances, such as serious illness, malnutrition, excessive fatigue or foreign stimuli, the body’s resistance will be reduced and some otherwise harmless bacteria may take advantage of the situation and cause harm to the body. These bacteria, which we call “opportunistic pathogens”, or “conditionally pathogenic bacteria”. During their growth and metabolism, they produce toxic and harmful substances, such as endotoxins, ammonia, amines, phenols, hydrogen sulfide and carcinogens, which must be removed in a timely manner by various means. The normal flora of the gastrointestinal tract can be divided into aerobic bacteria, parthenogenic bacteria and anaerobic bacteria. The most dominant is anaerobic bacteria, accounting for 99% of the total flora, of which only Bacteroides and Bifidobacterium account for 90%, while Lactobacillus and Bifidobacterium can be with us for life. After food or air enters the gastrointestinal tract, most of the microorganisms attached along with it can be killed by gastric acid, bile and other digestive juices. Therefore, the types and numbers of bacteria in the stomach and duodenum and jejunum are small, mainly aerobic bacteria and part-time anaerobic bacteria, such as streptococci, staphylococci and lactobacilli. The bacteria in the ileum begin to increase, with Lactobacillus, Escherichia coli, Bacillus-like bacteria, Clostridium and so on. In the colon, the types and numbers of bacteria increase more significantly, most of which are anaerobic bacteria, with bifidobacteria, bacilli and lactobacilli being absolutely dominant, while potentially pathogenic bacteria such as Clostridium perfringens and staphylococci account for only a very small number. The type, number ratio and distribution of flora vary according to the age, physical condition and diet structure of people. When an infant is first born, the respiratory and digestive tracts are sterile. With the first cry and the first swallow, microorganisms from the outside world enter the body. Unlike the respiratory tract, the gastrointestinal tract will soon reach its peak with the rapid proliferation of anaerobic bacteria, mainly bifidobacteria. At the stage of weaning and transition from mixed diet to adult diet, anaerobic bacteria such as Bacteroides and Eubacterium will become the dominant bacteria, and Bifidobacterium will gradually decrease to only 10% of the total number of bacteria. And infant type bifidobacteria, short bifidobacteria will gradually change to youth type bifidobacteria and adult type, long bifidobacteria. And the total number of E. coli and enterococci usually does not exceed 1%. Bifidobacteria in the elderly will be further reduced, some even completely undetectable bifidobacteria, while the detection rate of bacterium-like bacteria, Escherichia coli, Clostridium difficile, enterococci is significantly higher, this change is exactly synchronized with the aging of the body, the increase in disease, these bacteria produce toxic and harmful substances, so that the gastrointestinal tract condition corruption, promote the occurrence of infections, tumors and other diseases. This shows that the balance of the growth of the gastrointestinal flora and the growth and development of the human body, health status is inseparable. The human body’s resistance decreases, smoking, alcohol or diet is too stimulating, body temperature changes, etc., can cause changes in the internal environment, damage to the gastrointestinal mucosa, the number of normal flora is out of proportion, pathogenic microorganisms and toxic and harmful substances take advantage of the situation. Antibiotics, hormones, antineoplastic drugs and other chemicals are most likely to damage the internal environment and the normal flora of the gastrointestinal tract, leading to an increase in certain pathogenic microorganisms or the emergence of drug-resistant bacteria, and changes in the number, proportion and distribution of flora, leading to related diseases, such as abdominal pain, bloating, diarrhea, constipation, or even more serious problems. Protecting and regulating the number and proportion of normal flora in the gastrointestinal tract to resist various pathogenic microorganisms and remove toxic and harmful substances is a green ecological health care therapy that is currently highly recommended. Animal experiments have shown that germ-free mice are unable to excrete cholesterol and its degradation products through feces. In vitro tests have found that a certain percentage of Lactobacillus can inhibit the growth of H. pylori. These studies provide a scientific basis for further clinical medicine and show new and promising prospects for the treatment of hyperlipidemia and H. pylori infection. Chinese medicine can regulate human immunity, protect gastrointestinal mucosa, improve gastrointestinal function and internal and external environment, maintain the number and proportion of normal flora, inhibit harmful bacteria, Chlamydia, Mycoplasma, Leptospira, viruses, fungi, parasites, and remove toxic and harmful substances produced by them for a longer term by using natural drugs orally or externally, acupuncture and massage of meridian points, and swallowing jin. Effective disease prevention and treatment has highlighted great potential and advantages.