The early diagnosis of primary liver cancer (PLC) is crucial, and since the 1970s and 1980s, the early diagnosis of liver cancer has improved significantly due to the gradual and widespread use of serum alpha-fetoprotein (AFP), ultrasonography and CT. As the early diagnosis rate improved significantly, the surgical resection rate increased and the prognosis also improved significantly. Therefore, early diagnosis of hepatocellular carcinoma is the key to improve clinical efficacy and prognosis. For early diagnosis of liver cancer, full attention should be paid to the background of liver disease of patients. About 90% of patients with hepatocellular carcinoma in China have a background of hepatitis B virus (HBV) infection, some patients have a background of hepatitis C virus (HCV) infection, and some patients have overlapping HBV and HCV infection. It is currently believed that hepatitis B or C virus infection-hepatocellular atypia-hepatocellular carcinoma is the three-step process by which most hepatocellular carcinomas occur. For middle-aged and older men with high HBV load, HCV infection, HBV and HCV overlap infection, alcoholics, combined hepatic steatosis, diabetes or family history of liver cancer, regular screening tests such as serum AFP test and liver ultrasound should be performed every 6 months. Once elevated serum AFP or occupying liver lesions are detected, the patient must immediately enter the diagnostic process and be closely observed in an effort to make an early diagnosis. Laboratory diagnosis methods of hepatocellular carcinoma In China, the qualitative diagnosis of hepatocellular carcinoma is still based on the detection of serum AFP, which should be given great attention. It is reported that more than 60% of liver cancer patients in China have serum AFP > 400 μg/L; there is no other tumor marker with specificity comparable to AFP; AFP detection is less dependent on imaging equipment and new technology, and should be one of the preferred laboratory diagnostic bases. In recent years, the rapid development of medical imaging methods has provided a reliable basis for clinical diagnosis of hepatocellular carcinoma by “four definitions” (localization, characterization, quantification and regularity) and treatment plan. Ultrasound examination is non-invasive, which has no adverse effect on human tissues, simple operation, intuitive and accurate, low cost, convenient and non-invasive, and easy to be widely used in the screening and follow-up of liver cancer after treatment. Intraoperative ultrasound probes directly on the surface of the liver after opening the abdomen, avoiding ultrasound attenuation and interference from the abdominal wall and ribs, and can detect small intrahepatic lesions that cannot be detected by preoperative CT and ultrasonography techniques. However, ultrasonography is susceptible to the influence of factors such as the examiner’s experience, technique and meticulousness. 2.Multi-layer spiral CT CT is much higher in resolution than ultrasound, with clear and stable images, which can reflect the characteristics of liver cancer comprehensively and objectively, and can be used for routine diagnostic examination of liver cancer and follow-up examination after treatment.CT has the following advantages in diagnosing liver cancer: CT enhanced scan can clearly show the size, number, morphology, location, boundary, richness of blood supply of tumor and the relationship with intrahepatic ducts of liver; for CT scan can clearly show the size, number, shape, location, boundary, richness of tumor blood supply and relationship with intrahepatic ducts; it has important diagnostic value for whether there is cancer embolus in portal vein, hepatic vein and inferior vena cava, whether there is metastasis in hilar and abdominal lymph nodes, and whether hepatocellular carcinoma invades adjacent tissues and organs; it can also judge the severity of hepatic sclerosis by showing the shape of liver, the size of spleen and the presence of ascites. Especially, CT dynamic enhancement scan can significantly improve the detection rate of small hepatocellular carcinoma; CT scan after 3 to 4 weeks of iodine oil embolization of hepatic artery can also effectively detect small hepatocellular carcinoma lesions. 3.Magnetic resonance imaging (MRI) MRI has high tissue resolution, multi-parameter and multi-directional imaging, and no radiation effect, so MRI is another efficient and non-invasive diagnostic method for liver cancer examination after CT. The application of liver-specific MRI contrast agent can improve the detection rate of small hepatocellular carcinoma and help to differentiate hepatocellular carcinoma from focal hyperplastic nodules and hepatic adenoma; in addition, MRI has higher clinical value than CT for the follow-up of the efficacy of hepatic artery chemoembolization (TACE) in patients with hepatocellular carcinoma. MRI has unique features and can be an important supplement to CT examination. PET-CT is a functional molecular imaging system that integrates PET and CT. It can reflect the biochemical and metabolic information of liver occupancy by PET functional imaging, and can precisely locate the lesion by CT morphological imaging, and the whole body scan can understand the overall situation and evaluate the metastasis, so as to achieve early detection of the lesion. The purpose of early detection of lesions can be achieved, and the size and metabolic changes before and after tumor treatment can be understood. Selective hepatic arteriography is an invasive test, which can also be used for chemotherapy and iodine oil embolization and has therapeutic effect, and can clearly show small liver lesions and their blood supply.