B cell activating factor (BAFF) is the key regulator of B cells and is considered as a potential therapeutic target for immune inflammatory diseases. Periodontitis can promote local and systemic BAFF factor expression, whereas BAFF aggravates B cell immune responses and tissue destruction in periodontitis. In addition, BAFF also stimulates CD4⁺T cell response and inhibits regulatory T cell and M2 macrophage responses, thus changing the pathogenesis of a variety of immune inflammatory diseases. However, whether the biological effect mentioned above is an important mechanism by which BAFF aggravates periodontitis still lacks direct evidence and should be confirmed in future research. To provide a theoretical basis for the study of the pathogenic mechanism of BAFF, the expression and role of BAFF in periodontitis is reviewed in this article.