The source of hepatitis B virus infection is mainly acute and chronic hepatitis B patients and virus carriers, so hepatitis B virus carriers can spread hepatitis B virus and infectious diseases. The transmission route includes: 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. Among them, perinatal transmission or the delivery process is the main way of mother-to-child transmission. 2, blood, body fluid transmission: the 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 transmission routes: Although there is a theoretical possibility of transmission through the broken digestive tract, respiratory mucosa or insect bites, but the actual meaning of these transmission routes is not significant. It should be noted that people who are negative for hepatitis B surface antibody are all susceptible, and newborns of hepatitis B surface antigen (HBsAg)-positive mothers, family members of HBsAg-positive people, people with repeated blood transfusions and blood products, and medical workers who are exposed to blood are all high risk groups. It can be seen that hepatitis B virus carriers can transmit hepatitis B to susceptible people, and high-risk groups who do not have hepatitis B surface antibody should be vaccinated in a timely manner to prevent infection.