Abstract: Mother-to-child transmission (MTCT) is the main route of chronic hepatitis B virus (HBV) infection in China, and a systematic understanding of the mechanism MTCT of HBV and blocking strategies are of crucial for increasing the success rate of blocking. The combined immunization of hepatitis B immunoglobulin (HBIG) and hepatitis B vaccine (HepB) has achieved good efficacy, but failure in blocking often occurs. Intrauterine infection in pregnant women with high viral load is the main reason for failure, and the infection pathways include placental pathway, peripheral blood mononuclear cells (PBMCs) pathway, and infected germ cells pathway. Antiviral therapy during pregnancy can effectively block intrauterine infections, but various guidelines have not yet reached a consensus on the start time and the HBV DNA threshold. This paper summarized the mechanism and blocking strategies of MTCT in order to provide a reference for further increasing the success rate of blocking.