The synthesis of SP capsule polysaccharides is based on the common pathogenic serotype polysaccharides. As a kind of pathogenic bacteria widely distributed in common pathogenic serotype, 23F serotype streptococcus pneumoniae has been paid much attention to the research of chemical synthesis based on its polysaccharides. In the early 1980 s, Jennings group of SP23F capsular polysaccharide on the surface of the cell structure of repeat unit are expounded, and its structure is:32 P-(2 -)-P-D-Glcp (l a 4)-[a-Rhap-l (l) 2]-P-D-Galp-(1 a 4)-a-Rhapl, but not to disclose the experimental details. Subsequently, Roy's research group conducted an in-depth study on the structure of emps on the surface of SP23F cells by using methylation analysis and high-formate oxidation analysis.