Abstract: Objective:To optimize deproteinized technology of polysaccharide from Euryale petioles and pedicel. Methods:With the rates of deproteination and polysaccharide loss rate as indexes, four deproteination methods, including Sevag, trichloroacetic acid (TCA), papain and papain-TCA (papain hydrolysis followed by TCA precipitation) were compared in our study, the response surface methodology was performed with a Box-Behnken central compostite experiment to optimize deproteinization conditions, and the optimal process was treated with TCA once. Results:The optimal conditions were as follows:hydrolyzing substrates with papain dosage of 580 U·mL^-1, hydrolysis temperature of 30℃, hydrolysis time of 2.0 h, pH of 7.0, the concentration of TCA 8.0%.Under this condition, the deproteinated rate was up to 85.1%, and the rate of polysaccharide loss rate was 16.3%. Conclusion:The papain-TCA may become a great candidate for Euryale petioles and pedicel polysaccharides purification.