Abstract: In order to optimize ultrasonic-assisted extraction technology for the extraction of oligosaccharide from defatted soybean meal after extrusion, on the basis of single factor experiments, the effects of operating conditions, such as ultrasonic-assisted extraction time, ratio of solution to material and ethanol concentration on the yield of oligosaccharide were analyzed by response surface methodology. The optimized conditions of ultrasonic-assisted extraction are as follows: ultrasonic treatment time 34 min, ratio of solution to material 20.4 mL/g, and ethanol concentration 31.3%. Under the above-mentioned conditions, the actual yield of target oligosaccharide was 11.95%, increased by 50.31% compared with the control without ultrasonic assisted extration and extrusion which is in good agreement with the predicted yield. The above mentioned extrusion technology is in favor of oligosaccharide extraction, and ultrasonic assisted extraction method is better than ethanol extraction method in terms of yield and time.