Objective: To study the technological conditions of preparing rice bran dietary fibers by cellulase hydrolysis, and analyze the reasons for the difference in the functional properties of different rice bran dietary fibers. Methods: Single factor experiment was used to optimize the process conditions. The chemical composition, oil holding capacity and sodium cholate adsorption capacity of rice bran dietary fibers were measured. And the microstructures of rice bran dietary fibers were observed by scanning electron microscope. Results: When the dosage of cellulase was 100 U/g, the reaction time was 5 hours, and the ratio of material to liquid （m _{rice bran dietary fiber}∶V _water） was 1∶15 （g/mL）, there were no significant change in the yield of insoluble dietary fiber and soluble dietary fiber. After hydrolysis, the cellulose and hemicellulose content of rice bran dietary fiber decreased significantly （P＜0.05） from 26.23% and 28.71% to 18.29% and 25.24%, respectively. And the lignin content increased significantly （P＜0.05） from 20.22% to 31.46%. Scanning electron microscopy analysis indicated that the surface of the soluble dietary fiber was dense and smooth, without obvious pore structure, and the surface of the insoluble dietary fiber after hydrolysis showed more and deeper pore structure. The oil holding capacity of rice bran soluble dietary fiber, insoluble dietary fiber and dietary fiber without hydrolysis were 0.86, 5.21 and 4.15 g/g, respectively. And the adsorption rates of sodium cholate of rice bran soluble dietary fiber, insoluble dietary fiber and dietary fiber without hydrolysis were 15.17%, 24.04% and 20.84%, respectively. Conclusion: The differences in the functional properties of different rice bran dietary fibers are caused by the differences in their chemical compositions and fiber surface structures.