Abstract:Taking Alpinia zerumbet（Pers.）Burtt.et Smith as the test material，the response surface methodology was used to optimize the extraction process of Alpinia zerumbet polysaccharides，and the antioxidant activity of Alpinia zerumbet polysaccharides was studied. Ultraviolet spectrophotometry with glucose was used to establish a quantitative analysis method for the determination of polysaccharide content as the reference substance.On the basis of single factor experiment，taking extraction time，ultrasonic power and liquid-material ratio as independent variables，and polysaccharide yield rate as dependent variable，Box-Behnken design-response surface was used to optimize the extraction process of Alpinia zerumbet polysaccharides.The anti-oxidant activity of polysaccharide was studied by scavenging DPPH，superoxide anion and hydroxyl free radical.The results showed that the optimal extraction process conditions of Alpinia zerumbet polysaccharides were：extraction time 35 min，ultrasonic power 70 W，liquid-material ratio 40∶1（mL/g），and the polysaccharide yield was 5.37%.Polysaccharide had strong scavenging ability to DPPH，superoxide anion and hydroxyl free radicals.The higher the polysaccharide concentration，the stronger the antioxidant activity.