Bacterial secretion systems are responsible for the secretion of bacterial produced moleculars or DNA, and closely related to the growth and pathogenicity of bacteria. So far, seven types of secretion systems have been identified. TypesⅠ－Ⅵ exist in Gram－negatives and types Ⅳ and Ⅶ exist in Gram－positives. Type Ⅶ secretion system (T7SS) is identified recently. It is involved in the secretion of virulence－associated proteins, the interaction between pathogens and hosts, and the balance of zinc/iron ions, and is implicated in growth and pathogenesis of Gram－positive bacteria. The classification, regulation and biological functions of T7SS are reviewed in the present paper.