Liver cancer precursors are mainly nodule-like changes in the liver. These nodules have a unique appearance and generally show infiltrative growth, and in China, they are mainly found in patients with long-term alcohol consumption or poorly controlled hepatitis B and liver cirrhosis. There has been a relatively high incidence of hepatitis B and cirrhosis in China, as well as a large group of alcohol drinkers. This group of people can develop cirrhosis due to various reasons. In these groups, once irregular appearance of liver nodules is found, showing infiltrative growth, and obvious arterial phase enhancement is found when liver enhancement CT examination is performed, it needs to be considered as a precursor of hepatocellular carcinoma. In addition, some liver cancer patients may have no specific symptoms, but during physical examination, they are found to have excessive methemoglobin, and this situation also needs to be alerted to be caused by liver cancer. Generally speaking, if the level of methemoglobin is found to be too high during blood test or keeps rising after rechecking, further examination, including ultrasound, ultrasonography, enhanced CT or MRI, is needed to clarify the diagnosis. In addition, in terms of symptoms, persistent pain and discomfort in the right upper abdominal liver area that does not resolve after necessary treatment should also be alerted to the presence of this malignant disease. Hepatocellular carcinoma is a highly malignant disease, and the survival situation is generally not optimistic. The best way to deal with this disease is early detection, early diagnosis and early treatment.