Abstract: By taking the bamboo shoots as raw materials, the effect of ultra-fine pulverization-cellulase method on the modification of dietary fiber (DF) was evaluated. By detecting the yield, water-holding power and expansive force of soluble dietary fiber (SDF) in bamboo shoots, the effects of ultra-fine pulverization time (0-25 s), cellulase concentration (0.1%-0.5%), enzymolysis time (30-150 s), enzymolysis temperature (30-55℃) and pH value (4.5-5.5) on the modification of dietary fiber in bamboo shoots were analyzed. By taking the enzymolysis concentration, enzymolysis temperature, enzymolysis time and pH value of samples as the independent variables, and the yield of SDF in the samples as the response value, the Box-Behnken central composite design method was used to construct a Box-Behnken model with 4 factors and 3 levels, thus to analyze the DF modification technology of bamboo shoots. The results showed that the properties of DF in bamboo shoots after ultra-fine pulverization were significantly better than those without modification (P<0.05). The yield, water-holding power and expansibility of SDF in bamboo shoots increased with the extension of ultra-fine pulverization time within 0-10 s. The yield of SDF was (8.60±0.142) %, the water-holding power was (5.11±0.050) g·g^-1, and the expansibility was (11.06±0.067) mL·g^-1 after ultra-fine pulverization for 10 s. The yield, water-holding power and expansibility of SDF in bamboo shoots began to decrease with the further extension of ultra-fine pulverization time. In the range of cellulase concentration from 0.1% to 0.3%, the yield, water-holding power and expansive force increased with the increase of cellulase concentration. When the cellulase concentration was greater than 0.3%, the yield, water-holding power and expansive force of SDF in bamboo shoots decreased with the increase of the cellulase concentration. The best yield, water-holding power and expansive force of SDF in bamboo shoots were obtained after enzymatic hydrolysis for 60 min. When the pH reached 4.5, the yield, water-holding power and expansive force of SDF in bamboo shoots were the best. The most significant factor affecting the yield of SDF in bamboo shoots was the cellulase concentration (F=28.76), followed by the pH (F=18.05), enzymolysis time (F=11.43) and enzymolysis temperature (F=10.93). The Design Expert regression model analysis showed that the predicted yield of SDF in bamboo shoots reached 15.89% with the cellulase concentration being 0.32%, enzymolysis time being 85.03 min, enzymolysis temperature being 50℃, and pH value being 4.81.