Hepatitis B surface antibody of 300IU/L indicates that the human body is immune to the hepatitis B virus and does not need to be injected with additional hepatitis B vaccine. Hepatitis B surface antibody is an important indicator for detecting whether the human body has immunity against hepatitis B virus, which is a kind of protective antibody against hepatitis B surface antigen protein produced by the human body after being infected with hepatitis B virus. Hepatitis B surface antibody of 300IU/L indicates that the human body has immunity against hepatitis B virus and has produced strong protection. There is no need for additional vaccination against hepatitis B. If the hepatitis B surface antibody is between 10 and 100 U/L, a booster shot of hepatitis B vaccine is needed.