Primary liver cancer (referred to as hepatocellular carcinoma) is a common malignant tumor. Due to insidious onset, no or insignificant symptoms in early stage and rapid progress, most patients have reached locally advanced stage or distant metastasis when diagnosed, which makes treatment difficult and prognosis very poor, and natural survival time is very short if only supportive symptomatic treatment is taken. The etiological factors of liver cancer in China mainly include hepatitis virus infection, food aflatoxin contamination, long-term alcohol abuse and blue-green algae toxin contamination of rural drinking water, other liver metabolic diseases, autoimmune diseases and cryptogenic liver disease or cryptogenic cirrhosis. Since early diagnosis of liver cancer is crucial for effective treatment and long-term survival, early screening and early surveillance of liver cancer are highly emphasized. Routine surveillance screening indicators mainly include serum alpha-fetoprotein (AFP) and liver ultrasonography (US). For men ≥40 years of age or women ≥50 years of age with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infection, alcoholism, comorbid diabetes mellitus, and a family history of liver cancer, screening is generally performed at 6-month intervals. It is generally accepted that AFP is a relatively specific tumor marker for hepatocellular carcinoma (HCC), and persistent elevation of AFP is a risk factor for the development of HCC. Subclinical pre-stage of hepatocellular carcinoma refers to the period from the beginning of the lesion to the diagnosis of subclinical hepatocellular carcinoma when the patient has no clinical symptoms and signs and is difficult to detect clinically, usually about 10 months. In the subclinical stage (early stage) of hepatocellular carcinoma, the tumor is about 3-5 cm, most patients still have no typical symptoms and the diagnosis is still difficult, mostly detected by serum AFP census for about 8 months on average, during which a few patients can have symptoms related to chronic underlying liver disease such as epigastric stuffiness, abdominal pain, weakness and loss of appetite. Therefore, for those who have high-risk factors and the above-mentioned conditions occur, they should be alerted to the possibility of hepatocellular carcinoma.