The source of infection of hepatitis B virus is mainly acute and chronic hepatitis B patients and virus carriers, and the main transmission routes are as follows: 1. Mother-to-child transmission: is the most important transmission route of hepatitis B in China, including intrauterine infection, perinatal transmission and post-delivery transmission. Intrauterine infection is mainly acquired through the placenta, which may be related to the slight abruption of the placenta during pregnancy. Perinatal transmission or the delivery process is the main mode of mother-to-child transmission, where the infant is infected by contact with maternal blood, amniotic fluid or vaginal secretions from broken skin or mucous membranes. Post-delivery transmission is mainly due to intimate contact between mother and baby. 2, blood, body fluid transmission: blood contains high levels of hepatitis B virus, such as blood transfusions and blood products, injections, surgery, sharing razors and toothbrushes, hemodialysis, etc. can be transmitted. In addition. It has been confirmed that saliva, sweat, semen, vaginal secretions, breast milk and other body fluids contain hepatitis B virus, close contacts, sexual contact, etc. are also possible ways to obtain hepatitis B virus infection. 3, other means of transmission: Although there is a theoretical possibility of transmission through the broken digestive tract, respiratory tract mucosa or insect bites, but in practice these means of transmission are not very significant. It should be noted that although hepatitis B is contagious, normal daily contact with people infected with the hepatitis B virus, such as working together, holding hands, hugging, living in the same room, dining together, etc., will not cause the transmission of the hepatitis B virus. In addition, hepatitis B vaccination is a reliable way to prevent hepatitis B. The hepatitis B vaccination can stimulate the body to produce hepatitis B surface antibodies, which can protect the body from being infected by the hepatitis B virus. As mentioned above, hepatitis B virus can be transmitted through mother-to-child transmission, blood transmission, close contact transmission, sexual contact transmission, etc. People who do not have hepatitis B surface antibodies should be vaccinated in time to prevent infection.