Objective:To study the preparation process of carboxymethylated pumpkin polysaccharide and evaluate its antioxidant and hypoglycemic activity in vitro.Methods:Monochloroacetic acid concentration, reaction temperature and reaction time were further optimized by single factor tests and response surface tests, and the antioxidant activity test and hypoglycemic test were also carried out.Results:The optimum preparation conditions of carboxymethylated pumpkin polysaccharide were as follows: the concentration of monochloroacetic acid of 1.9 mol/L, reaction temperature of 73 ℃, reaction time of 3 h. Under the preparation conditions, the substitution degree of carboxymethyl polysaccharide was 1.247. Studies on antioxidant activity have shown that, within a certain range of mass concentrations, there was a dose-dependent relationship between antioxidant ability and mass concentration of pumpkin polysaccharide (PP) and carboxymethylated pumpkin polysaccharide (CM-PP). Hypoglycemic test showed that carboxymethylation of pumpkin polysaccharides also increased the inhibitory activity of α-glucosidase compared with the pumpkin polysaccharides before modification.Conclusion:The optimized technology of carboxymethylated pumpkin polysaccharide is reasonable and feasible, and has strong antioxidant activity and hypoglycemic activity.