Abstract: The pathogenesis mechanism of Mycoplasma suis is reviewed in this paper.It includes four facts. The first one is that Erythrocyte membrane alterations associated with the attachment and replication of M.suis and autoimmune hemolytic anemia. The second one is that it makes pigs produce cold agglutinins of immunoglobulin type IgM and causes Erythrocyte agglomeration and lyses and makes pigs occur the Ⅱ tape allergic response. The third one is that it makes glucose in blood decrease and body occur acidosis. So red blood cell infected by M.suis decreases the ability that takes along aerobic and causes a disturbance of pulmonary gaseous exchange. The last one is that it induces severe parasitemia suppression and misleads pig’s immunoreaction.

Key words: Mycoplasma suis; pathogenesis mechanism; hemolytic anemia; cold agglutinins