Abstract: Based on the single factor experiments of ultrasonic extraction and complex enzyme hydrolysis,the response surface analysis was used to optimize the conditions for the stepwise extraction of Brassica rapa L.polysaccharides by ultrasonic synergistic complex enzyme using extraction rate of Brassica rapa L.polysaccharides as the index. Results showed that,the optimal extraction process of ultrasonically synergistic compound enzyme for stepwise extraction of Brassica rapa L. polysaccharides was as follows:Liquid to material ratio 33:1 mL/g,ultrasonic temperature 62℃,ultrasonic power 250 W,ultrasonic extraction for 43 min,and addition of 2.5% of the complex enzyme(cellulase:papain:pectinase=1:1:1,w/w),enzymatic hydrolysis pH5.4,enzymatic hydrolysis temperature 50℃,enzymatic hydrolysis time 52 min. Under these conditions,the yield of Brassica rapa L. polysaccharide was 12.62%±0.18%. Ultrasonic synergistic compound enzyme stepwise extraction of Brassica rapa L. polysaccharides had a high yield,and the process was simple and easy to apply,which would be suitable for the extraction of Brassica rapa L.polysaccharides.