It is well known that China is one of the countries with a high prevalence of hepatitis B virus infection, and the survey data on the prevalence of viral hepatitis published in 1997 showed that the rate of HBsAg carriers in China is 9.75%, which means that there are hundreds of millions of HBsAg carriers in China. These people are not hepatitis B patients. HBV transmission route HBV exists in the blood, body fluids, various secretions and excretions of hepatitis B patients and HBsAg carriers. These body fluids containing HBV have different degrees of significance for the transmission of hepatitis B virus. 1, perinatal transmission from mother to child This is an important route of HBV transmission recognized worldwide, the highest is in Asia, followed by Africa, the United States and Western countries are smaller. HBsAg positive rate of HBsAg in newborns of HBsAg positive mothers, in Europe, the United States 10%, Africa 25-30%, Asia 30-70%, China about 60%. 2, blood transfusion, injection transmission, including blood transfusion and blood products transmission, needle prick, tattoo, cut and tie can also cause transmission. Repeated blood tests, multiple injections, frequent invasive tests and diagnostic measures, etc. 3, broken mucous membrane transmission HBsAg and Dane particles can be found in semen and vaginal secretions, which can be transmitted sexually, so hepatitis B is one of the sexually transmitted diseases. Damage to oral mucosa can also cause transmission. Second, precautions 1, from a medical point of view, HBsAg carriers do have some weaknesses in the body in terms of immune mechanisms to clear HBV, they should be under regular medical observation, in life should avoid overwork, pay attention to the combination of work and rest, maintain a happy mood, improve personal hygiene literacy, consciously prevent their own blood, saliva, urine and other body fluid secretions contamination of the surrounding environment; use and keep a good personal HBsAg carriers should also pay attention to the protection of the liver, abstain from alcohol, prohibit the use of drugs that damage the liver, and pay attention to the prevention and treatment of other diseases, especially infectious diseases, to avoid further damage to the liver. 2, in the medical observation and follow-up, every six months to a year should be a follow-up examination, self-perception of abnormalities at any time to seek medical attention. Follow-up examinations should include physical examination, liver function, serum HBV infection indication and liver B-type ultrasound examination, and serum alpha-fetoprotein should be tested for those over 40 years old in order to detect changes in condition and take corresponding treatment measures.