Positive hepatitis B surface antigen is a sure sign of hepatitis B virus infection. Hepatitis B surface antigen is one of the serologic markers of hepatitis B, and it is the earliest pathogenetic marker of hepatitis B virus infection. Hepatitis B surface antigen can be positive at the same time as other pathogenetic markers, but as long as the hepatitis B surface antigen is positive, it indicates that the hepatitis B virus is infected, which can be a carrier of the hepatitis B pathogen, or a patient with chronic hepatitis B. The patient can also develop cirrhosis of the liver and hepatocellular carcinoma of the hepatitis B. The hepatitis B surface antigen can be cleared on its own. The probability of chronic hepatitis B surface antigen clearing by itself is less than 2%, if it is acute infection of hepatitis B virus 90% can be clinically self-healing, manifested as hepatitis B surface antigen can be cleared, and gradually produce hepatitis B surface antibody, if the hepatitis B surface antigen continues to be positive for more than six months, that is, chronic hepatitis B virus infection.