Abstract: 【Objective】 To optimize the extraction process of unhulled quinoa seed polysaccharides by cellulase and evaluate its antioxidant activity.【Method】 Enzymatic hydrolysis crushed,sieved and defatted quinoa seeds with cellulase based on the single-factor test,the four-factor three-level response surface optimization test of extraction temperature,material-to-liquid ratio,extraction time and enzyme concentration was carried out,and the scavenging rate of polysaccharides on hydroxyl radicals,DPPH and ABTS+ radicals was studied.【Result】 The best extraction effect was achieved at a temperature of 60 ℃,a material-toliquid ratio of 1∶20,a time of 2. 0 h and an enzyme concentration of 5%,and the extraction rate could reach 5. 16%. The scavenging rates of quinoa polysaccharide on hydroxyl radical and DPPH radical were 60. 55% and 44. 04%,respectively,and the effect was remarkable. The radical scavenging rate of ABTS+was 9. 09%.【Conclusion】 This study provides a basis for the extraction and utilization of quinoa polysaccharides.