The invention relates to a preparation method of high-dietary-fiber oleogel. The preparation method comprises the steps of preparing cellulose water dispersion, mixing the cellulose water dispersion and hydrophilic colloid, dispersing oil phase in the mixed system to prepare oil-in-water emulsion, and treating the oil-in-water emulsion to obtain the oleogel, or adding food additives to promote the emulsion to form gel to obtain the oleogel, wherein the treatment method comprises a drying method and a freezing method. Cellulose particles service as emulsifiers, the hydrophilic colloid serves as a stabilizer and a thickening agent, the cellulose particles are irreversibly adsorbed on the oil water interface, the hydrophilic colloid intersperse the cellulose network structure to jointly form a three-dimensional network structure, liquid fat can be constrained efficiently, the prepared emulsion gel has high stability, and long-time storage and transportation are facilitated; the method is simple, convenient, high in dietary fiber content of the prepared high-dietary-fiber oleogel, economic and environmentally friendly; the oleogel is physical gel, does not change the chemical property of the oil phase, avoids generation of trans-fatty acid, and has good application prospect in the fields of food, medicines and cosmetics.