Primary liver cancer is widely prevalent in China, and it is called the “king of cancers” because of its short course, high death rate and great danger. By understanding the common causes of primary liver cancer, early prevention, early detection, early diagnosis and early treatment can be achieved. There are many factors leading to liver cancer, some of which are not really understood yet, but a lot of progress has been made. The common causes are as follows: 1. Viral hepatitis infection and cirrhosis: viral hepatitis is considered to be an important cause of hepatocellular carcinoma. Recent studies have shown that viral hepatitis is easily related to liver cancer involving three kinds of viral hepatitis B dry eye virus (HBV), hepatitis C virus (HCV) and hepatitis D virus (HDV). In particular, the closest relationship is with hepatitis B and C. Hepatitis virus DNA or viral products can enter hepatocytes and activate cellular oncogenes leading to carcinogenesis. About half of the patients with hepatocellular carcinoma have a clear history of hepatitis. Among hepatocellular carcinoma patients, HBsAg-positive patients account for more than 80%; the incidence of liver cancer is more than 10 times higher in HBsAg-positive people than in HBsAg-negative people. Cirrhosis is the result of chronic hepatitis and further changes in the disease can develop into liver cancer. The incidence of liver cancer combined with liver cirrhosis is about 80%, especially with large nodular cirrhosis of hepatitis B and C, which is most closely related to liver cancer. This kind of cirrhosis is mostly caused by viral hepatitis, which has heavy damage to hepatocytes and a short disease duration, and often causes large nodular cirrhosis, which has more obvious proliferation and more chances to produce mutations. The prevalence of hepatocellular carcinoma increases from the age of 20 years and peaks at the age of 40-60 years, while the prevalence of hepatitis begins to increase 10-20 years earlier, suggesting a relationship between the two. It is also believed that chronic hepatitis can lead directly to the development of liver cancer without going through the cirrhosis stage. Other causes of cirrhosis such as primary biliary cirrhosis, alcoholic cirrhosis, schistosomiasis cirrhosis, etc. also have complications of liver cancer. 2.Mycotoxin contamination: Experiments have shown that aflatoxin and other mycotoxins can lead to liver cancer and a series of other cancers. Moldy corn, peanuts, wheat, cotton seeds, etc. contain high levels of aflatoxin, and the high incidence of liver cancer has been confirmed in areas with a high incidence of population after use. The more aflatoxin intake, the higher the incidence of liver cancer. 3.Drinking water pollution: There are many toxic and carcinogenic substances in polluted water, such as nitrosamines, hexachlorobenzene, blue rate algae and so on. In areas with high incidence of liver cancer, the pollution of quoted water is often serious, especially the ditch and pond water is easy to grow blue-green algae, and blue-green algae can produce a kind of “microcystin”, which is proved to be a strong cancer-promoting agent of liver cancer. 4. Individual susceptibility: Although the incidence rate of liver cancer can be as high as 0.1% or more in areas with high incidence of liver cancer, the majority of residents do not suffer from liver cancer. In the same environment, only a few people are still susceptible to liver cancer, which may indicate that the development is related to individual susceptibility. Individual susceptibility can either originate from a family with a high prevalence of the disease with genetic factors or be acquired. The above factors can be induced individually, but it is now believed that liver cancer is often caused by multiple factors in concert, such as the combined effect of various environmental factors and individual susceptibility, and the synergistic carcinogenesis of hepatitis B virus and aflatoxin.