In non-active or cured patients with hepatitis B virus (HBV) infection, when the body′s immune homeostasis is broken, HBV reactivation may occur, with the manifestations of liver inflammation and increased HBV DNA level, and lead to varying degrees of abnormal liver function, liver failure, and even death. Systematic management from the aspects of the screening of HBV reactivation, risk stratification of immunosuppression regimens, and patient's individual information needs to be solved urgently. It is very important to perform the screening of HBV serological markers before immunosuppressive therapy and chemotherapy, evaluate the risk of HBV reactivation, and develop individualized prophylactic antiviral therapy. Complete removal of covalently closed circular DNA in hepatocytes is essential for preventing HBV reactivation. This article summarizes related research advances in HBV reactivation from the aspects of its etiology, pathogenesis, diagnosis, prevention, and treatment.