High mobility group protein B1 (HMGB1) is a kind of nuclear protein widely existing in cells, which is released or secreted from cells by stress in the body and plays a key role in the survival or death pathways of cells. HMGB1 has a huge biological function and is the main regulator of major diseases such as inflammatory diseases and tumors. HMGB1 is closely related to the proliferation, differentiation, migration, apoptosis and drug resistance of tumor cells. With the continuous deepening of research on HMGB1, it is found that HMGB1 plays an important role in the occurrence, development, metastasis and drug resistance of breast cancer. Combined with the research status of HMGB1, the expression of HMGB1 in breast cancer is discussed to provide a new therapeutic scheme for clinical treatment.