Abstract: Many pathogenic microorganisms could produce many kinds of extracellular products indlucing protease, phospholipase, lipase, gelatinase, hemolysin and so on. The gelatinase, protease, amylase, phospholipase produced by the microorganisms were extracellular enzymes, they could play synergistic action with hemolysin in the pathopoiesis of bacteria to break down the tissue composition of host. The pathogenic extracellular products of pathogenic microorganisms and their reseach methods were summarized by the writer.