Hepatitis B surface antibodies are protective antibodies that protect against the hepatitis B virus and thus protect the body from hepatitis B virus infection. The hepatitis B virus is a DNA virus, and we have developed a series of serological indicators to detect the infection of the virus according to its biological characteristics, including hepatitis B surface antigen, antibody, hepatitis B e antigen, antibody and hepatitis B core antibody, commonly known as hepatitis B two-and-a-half indicators, of which hepatitis B surface antibody is the only protective antibody. Hepatitis B surface antibody is exactly an antibody produced by the body’s immune system against the surface antigen of the hepatitis B virus, which is protective for us. It binds to the surface antigen of the hepatitis B virus and plays a role in defending against the invasion of the hepatitis B virus. For patients infected with the hepatitis B virus, if the body has a powerful immune system that produces enough indicated antibodies to neutralize the surface antigen, the hepatitis B virus that has invaded the body will be gradually removed and the five tests for hepatitis B will show a negative hepatitis B indicated antigen and a positive hepatitis B surface antibody, core antibody and e antibody. In addition, the immune system of those who have not been vaccinated against hepatitis B will also produce protective hepatitis B surface antibodies, which will give the body immunity against hepatitis B. At this time, the five tests for hepatitis B will only show positive surface antibodies, while the hepatitis B surface antigen, core antibodies and e antibodies will be negative. In summary, hepatitis B surface antibodies are protective antibodies used to protect the body. Patients recovering from previous hepatitis B virus infection and hepatitis B vaccination patients may show positive results, which need to be further analyzed in conjunction with other indicators.