Medical imaging examination provides a reliable basis for clinical liver cancer localization and diagnosis and surgical plan formulation. Ultrasonography Ultrasonography is a non-invasive examination without any adverse effects on human tissues, and can be used for the screening and post-treatment follow-up of liver cancer. Real-time ultrasonography has important clinical value for the diagnosis of small hepatocellular carcinoma and is often used for the differential diagnosis of hepatocellular carcinoma. Intraoperative ultrasound can detect small intrahepatic lesions that are not detected by preoperative CT and ultrasound. The disadvantages of ultrasound examination are that it is susceptible to gas interference, more artifacts and larger horizontal images of the examined patient. Tomography (CT) Modern CT is very widely used, because its image is clear and stable, and can reflect the characteristics of liver cancer comprehensively and objectively, so it is often used for routine diagnostic examination of liver cancer and follow-up examination after treatment. Therefore, CT has become an important routine tool for liver cancer diagnosis. Especially, CT dynamic enhancement scan can significantly improve the detection rate of small liver cancer. Magnetic resonance imaging (MRI) MRI is another efficient and non-invasive diagnostic method for liver cancer examination after CT because of its high tissue resolution, multi-parameter and multi-directional imaging, and the absence of radiation effects. 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 hepatocellular carcinoma patients. MRI has unique features and can be an important supplement to CT. 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. The purpose of early detection of lesions, and the size and metabolic changes before and after tumor treatment can be understood. Selective hepatic arteriogram Selective hepatic arteriogram is an invasive examination, while chemotherapy and iodine oil embolization are also therapeutic, which can clearly show small lesions in the liver and their blood supply, and selective hepatic arteriogram is suitable for patients whose diagnosis cannot be confirmed after other examinations.