Liver cancer is a kind of tumor that seriously threatens the health and life safety of our people. In China, the incidence rate of liver cancer ranks the second highest among malignant tumors. The malignant degree of liver cancer is very high, because there are often no symptoms or symptoms are not obvious at the beginning of the disease, coupled with the rapid progress of the tumor, when it is diagnosed, about 70-80% of patients can no longer receive surgical treatment, and the treatment effect is very poor and the survival period is very short. The key to improve the cure rate of liver cancer is early diagnosis and early treatment. Then how to diagnose liver cancer at an early stage? At present, experts at home and abroad agree that monitoring and screening for high-risk people is the most important way to diagnose liver cancer at an early stage. Who are the high-risk groups of liver cancer? The causes of liver cancer in China mainly include the following aspects: 1. hepatitis virus infection; 2. long-term alcoholism; 3. environmental factors: such as aflatoxin contamination of food and blue-green algae toxin contamination of rural drinking water; 4. other liver diseases: such as liver metabolic diseases, autoimmune diseases, cryptogenic cirrhosis, etc. It is generally believed that about 90% or more of liver cancer patients in China are combined with hepatitis B or C infection. Therefore, chronic hepatitis B, chronic hepatitis C patients and long-term alcoholics are all high-risk groups for liver cancer, and those with family history of liver cancer need to be closely monitored. How to conduct surveillance for high-risk groups? Generally speaking, monitoring includes two aspects: on one hand, blood tests, mainly serum fetoprotein, which is a more specific tumor marker for liver cancer and its continuous elevation often indicates the occurrence of liver cancer; on the other hand, imaging tests, including liver ultrasound, enhanced CT, enhanced MRI, etc. We suggest that for people at high risk of liver cancer, they should preferably be examined every six months, with serum fetoprotein test and abdominal ultrasound examination preferred. For liver nodules larger than 1 cm detected by abdominal ultrasound, enhanced CT or enhanced MRI should be performed to clarify the nature of the nodules. It is especially important to point out that a recently introduced MRI enhancer called Promethazine has greatly improved the diagnostic sensitivity of liver lesions and is now recommended as the first choice of MRI enhancer for screening liver cancer in some countries including Japan. In conclusion, for people at high risk of chronic hepatitis, alcohol abuse and other exposure to adverse factors that predispose to liver cancer, it is necessary to undergo serological examination and liver ultrasound every six months, and if liver nodules are considered likely to exist, enhanced CT or enhanced MRI of the liver is recommended to further clarify the nature of liver nodules. For liver cancer, early diagnosis means the chance of early treatment and better treatment outcome.