In China, there are many asymptomatic carriers of hepatitis B. According to the statistics in the early 1990s, there were about 130 million HBsAg-positive carriers, accounting for about 10% of the total population. The incidence rate has only decreased after 2000, especially in the last decade, due to the intensification of hepatitis B vaccination, especially after the Ministry of Health introduced free vaccination since June 2005. In clinical practice, the clinical types of hepatitis B virus infection are often divided into three types according to the period of hepatitis B virus infection and the degree of liver function damage: 1. acute hepatitis B 2. chronic hepatitis B 3. asymptomatic carriers of hepatitis B virus. Acute hepatitis B is defined as never having been infected with hepatitis B virus before and recently found to have indicators of hepatitis B virus infection and evidence of liver function impairment for a period of less than six months. Chronic hepatitis B is defined as infection with the hepatitis B virus for more than six months with abnormal liver function. Strictly speaking, the term “chronic hepatitis B” refers to a person who has been infected with the hepatitis B virus for six months or more and has persistent abnormal liver function. According to the serology, virology, biochemistry tests and other clinical and auxiliary examination results of HBV-infected patients, chronic HBV infection can be divided into four major categories: (a) chronic hepatitis B 1. HBeAg-positive chronic hepatitis B Serum HBsAg, HBVDNA and HBeAg positive, anti-HBe negative, serum ALT persistently or repeatedly elevated, or liver histological examination with hepatitis lesions. 2. HBeAg-negative chronic hepatitis B Positive serum HBsAg and HBVDNA, persistently negative HBeAg, positive or negative anti-HBe, persistently or repeatedly abnormal serum ALT, or hepatitis lesions on liver histological examination. (II) Hepatitis B cirrhosis (III) Carriers 1. Chronic HBV carriers: positive serum HBsAg and HBVDNA, positive HBeAg or anti-HBe, but more than 3 consecutive follow-ups within 1 year, serum transaminases always in the normal range, and generally no significant abnormalities in liver histological examination. Those who are positive for HBVDNA should be mobilized for liver puncture examination (i.e. liver biopsy) for further confirmation of diagnosis and corresponding treatment. 2, inactive HBsAg carriers: serum HBsAg positive, HBeAg negative, anti-HBe positive or negative, undetectable HBVDNA by PCR or below the minimum detection limit, more than 3 follow-ups in 1 year, ALT are in the normal range. HAI on liver histology is less than 4. (iv) Occult chronic hepatitis B This is a category of conditions that must be given high priority, with negative serum HBsAg but positive HBVDNA in serum and/or liver tissue and clinical manifestations of chronic hepatitis B. The 3 antibody positivity seen clinically may also belong to this category; the other about 20% of patients with occult chronic hepatitis B are negative for HBV serologic markers except for HBVDNA positivity, (most hospitals cannot check for pre-S1, pre-S2 proteins specific to hepatitis B virus, if this test is positive, even if the DNA is negative, it should be considered as having HBV infection) For this special case, the diagnosis In such special cases, it is necessary to exclude other viral and non-viral factors causing liver injury.