Abstract: The chemical components of Caesalpinia spinosa seeds,the chemical structure and its rheological properties of polysaccharide gum were discussed.It was determined that endosperm accounted for about 30.5% of the total weight of Caesalpinia spinosa seeds and the protein content reached 13.2% of the seed weight.Analyses by GC,PC,IR and NMR showed that the endosperm of Caesalpinia spinosa seeds contained 78.0% of galactomannan with galactose to mannose rationed by 1:2.4.The chemical structure of galactomannan is β-(1,4)-linked D-mannopyranosyl residues as the main chain and α-(1,6)-linked D-galactopyranosyl residues in the side chain.Caesalpinia spinosa polysaccharide gum is non-newton fluid.Its viscosity of 1% concentration is 313 mPa.s(30℃,170S^-1).And Caesalpinia spinosa polysaccharide gum can be synergistic thickening and synergistic gelling with Xanthangum or carrageenan.