AIM: To explore the technology of extraction, isolation and purification of angelica sinensis polysaccharide(AP), to optimize the synthetical technology of dexamethasone hemisuccinate(DSH) and dexamethasone prodrug based on angelica sinensis polysaccharide(DEX-AP), to investigate the characteristics of colon-targeted delivery of the prodrug and to improve the study and development of colon-targeted drug delivery system.METHODS: 1. The fresh plant DangGui from Min county was circumfluenced in 80% ethanol to remove the lipophilic fraction. Rude polysaccharide was obtained by adding ethanol to its concentrated solution extracted in distilled-water. The rude polysaccharide was dissolved in water and deproteinized by freeze-thawing, then the polysaccharide was isolated into different fractions by ultrafiltration. The total sugar concentration and the protein concentration of these fractions were determined. 2. With 4-DMAP as