Response surface methodology (RSM) was applied to optimize the ultrasound-assisted extraction (UAE) of dietary fiber (polysaccharides) from Citrus Changshan-huyou peels. Box-Benhnken experimental design (BBD) was used for experimental design and data analysis was conducted to obtain the optimum extraction conditions. Results: The obtained optimum conditions were material/water ratio 1:37 (g/mL), extraction time 20 min, extraction power 60 W, extraction temperature of 70 ℃ and sodium hexametaphosphate 2 wt%. Under the optimized conditions, the yield of dietary was 6.62%, in close agreement with values predicted by the mathematical model. The content of polysaccharide in the product is 29.3 g/L. Compared with Conventional solvent extraction (CSE), UAE performed better to extract dietary fiber