Abstract: This paper studies extracting water-soluble dietary fiber (SDF) from hulls in order to improve SDF yield. Based on single-factor experiments, response surface analysis method was used to optimize extraction technology of water-soluble dietary fiber (SDF) in sunflower seed shell. The results showed that the optimum process parameters of soluble dietary fiber in sunflower seed shell were the following: NaOH mass fraction 7.83%, the extraction time 69.46 min, extraction temperature 42.10℃, ratio of liquid to solid 40 mL/g, with which yield of water soluble dietary fiber was up to 31.1112%. In addition, the water retention and swelling of SDF were also measured. The results indicated that soluble dietary fiber from sunflower seed shell had good water retention and swelling: water holding capacity 7.293 g/g, 3.997 mL/g swelling. Therefore, sunflower seed shell is good source of soluble dietary fiber.