Abstract: In order to acheive mass production of antioxidant peptides from quinoa chaff with the best antioxidant activity,the enzymatic hydrolysate from quinoa chaff protein was made through enzymolysis used flavor enzyme and alkaline enzyme. The antioxidant peptide of quinoa chaff with different molecular mass were purified by ultrafiltration technology. Antioxidant activity in vitro were measured and evaluated to optimize and select in order to get the antioxidant peptides with the best antioxidant activity. Took membrane flux as the index,the stress,time and filtrate quality score as 3 process parameters. The optimum technological conditions of the ultrafiltration of 10 ku ultrafiltration separation of antioxidant peptides from quinoa chaff were studied by the combination of single factor and orthogonal test. The results showed that,the ultrafiltration components with different molecular weights had different antioxidant activity,of which the antioxidant peptide of 5~10 ku had better antioxidant activity than the others ultrafiltration components of different molecular weights.The optimal ultrafiltration conditions of antioxidant peptides from quinoa chaff were pressure 0.16 MPa,20 min time,2% of filtrate quality score,and the maximum amount of membrane flux in the condition was(41.22±0.50) L/m²·h.Thus,the production of antioxidant peptides from 5~10 ku can be achieved.