Primary liver cancer (hepatocellular carcinoma) is one of the most common malignant tumors in China, and its incidence rate ranks second among malignant tumors in China, with more than 200,000 people dying of liver cancer every year, accounting for about 50% of the total number of deaths in the world. Although China has invested a lot of human and material resources in the prevention and treatment of liver cancer for more than 30 years and achieved fruitful research results, it has not fundamentally changed the prognosis of liver cancer, and the ratio of incidence rate to mortality rate is still almost 1:1. To change the prognosis of liver cancer patients and prolong their survival, the key lies in early detection, early diagnosis and early treatment. Early treatment is the most important way for liver cancer patients to obtain long-term survival, the survival rate of 5 years after resection of early stage liver cancer in China reaches 60-70%, and the longest survival is over 40 years, which is a leading position in the international arena and has changed liver cancer from an incurable disease to a partially curable disease. So how to detect early liver cancer? It is mainly through the monitoring of high-risk groups. What is the high-risk group of liver cancer? Those who meet one of the following conditions 1.Age over 35 years old and positive for hepatitis B virus surface antigen (HBsAg) 2.History of hepatitis B or C (active hepatitis) for more than 5 years 3.Any type of cirrhosis 4.Family history of liver cancer (with different views, mainly common living environment) . Liver ultrasound and serum alpha-fetoprotein (AFP) are the most important monitoring tools for people with high risk of liver cancer, which is tens to hundreds of times more likely than normal people. Therefore, anyone who belongs to the high-risk group of liver cancer should take the initiative to go to the hospital for examination every 4-6 months, which can theoretically detect all small liver cancers under 3 cm in diameter.