Response surface methodology was used to optimize the ultrasonic extraction process of saponins from the bran of Chenopodium quinoa Willd.and the inhibitory activity of the extract against α-glucosidase was investigated under the optimal extraction conditions.The enzyme reaction kinetics equation was established to analyze the inhibition kinetics and mechanism.The results showed that the optimal extraction conditions of saponins from quinoa bran were as follows:liquid-solid ratio of 15 mL/g,ultrasonic extraction with 75% ethanol,ultrasonic time of 1.5 h,ultrasonic temperature of 45 ℃.Under these conditions,the extraction yield of saponins from quinoa bran was 2.370% ± 0.022%.α-Glucosidase inhibitory activity of the extract was stronger than that of acarbose (P < 0.05),and the IC₅₀ value was 0.620 ± 0.057 mg/mL.Enzyme kinetics study showed that total saponins extract of quinoa bran was a reversible mixed inhibition type.This study provides a reference for clarifying the mechanism of quinoa bran extract in reducing postprandial blood glucose and a basis for the development and utilization of quinoa bran.