Hepatitis B surface antigen 250IU/ml is potentially contagious. Laboratory pathogenetic tests show that hepatitis B surface antigen test value > 0.05IU/ml represents positive, so hepatitis B surface antigen 250IU/ml is a positive result, indicating that the patient has been infected with the hepatitis B virus and the hepatitis B virus is very active in the body, and at the same time, hepatitis B surface antigen is positive is infectious. Hepatitis B surface antigen is the first serologic marker that appears after hepatitis B virus infection, and it is one of the important indicators for diagnosis. Hepatitis B surface antigen positivity is seen in acute hepatitis, chronic hepatitis, or asymptomatic carriers, all of which are infectious. Hepatitis B virus infection is mainly transmitted by blood, mother-to-child transmission and sexual transmission, so in order to prevent transmission to others in daily life, patients should avoid sharing toothbrushes, razors and other items with other people, and avoid sexual intercourse until the disease is stabilized. It is recommended that when the surface antigen of hepatitis B is 250IU/ml, the patient should actively cooperate with the doctor to carry out further examination, such as doing hepatitis B DNA test, the higher the level of hepatitis B DNA indicates that the virus is more replicated and infectious, and carry out the treatment under the guidance of the doctor.