Abstract: The study focused on ultrasound- coupled enzymatic hydrolysis to produce xylooligosaccharides from cottonseed husk by response surface methodology.The conditions of ultrasound- coupled enzymatic hydrolysis were optimized by response surface methodology,and its mathematical model was established. Results showed that the optimal parameters of ultrasound- coupled enzymatic hydrolysis were as follows: the initial p H5.1,hydrolysis time 42 min,temperature 45 ℃,ultrasonic frequency 40 k Hz,ultrasonic intensity 0.22 W / cm2. Under the optimal conditions,the conversion ratio of reducing sugar reached 50.46%.Moreover,the components of ultrasound- coupled enzymatic hydrolysis were measured by HPLC,the conversion ratio of xylobiose was 29.38%,accounted for 58.22% of the total reducing sugar.