Hepatitis B surface antibody is weakly positive due to two reasons, one is that the body produces antibody after previous injection of hepatitis B vaccine, and the other is that the body has been infected with hepatitis B virus in the past, but the body destroys the virus through the immune system and produces hepatitis B surface antibody. Hepatitis B surface antibody is one of the five items of Hepatitis B. It is the corresponding antibody produced by the immune system after the surface antigen of Hepatitis B virus stimulates the body, and it is the protective antibody of the body, which protects the body from being attacked by Hepatitis B virus again. Hepatitis B surface antibody decreases with time and repeated depletion, which is manifested as weak positive or even negative in blood test, at this time, the protective property of hepatitis B surface antibody is weak. If the titer of hepatitis B surface antibody is lower than 10, it is necessary to receive hepatitis B vaccine again to stimulate the body to produce hepatitis B surface antibody to protect the body from hepatitis B virus infection. Hepatitis B surface antibody weak positive, need to go to the hospital, under the guidance of the doctor to clarify the situation.