Method for preparing cannabidiol

The invention provides a method for preparing cannabidiol. The method comprises the following steps: providing a plant source with cannabidiol as a raw material, crushing the raw material, mixing thecrushed raw material, water and a biological enzyme, and performing an enzymolysis reaction, performing filtering so as to obtain an enzymolysis liquid and enzymolysis residues; mixing the enzymolysisresidues with an extraction solvent, and performing flash extraction at room temperature, wherein the mass ratio of the enzymolysis residues to the extraction solvent is (1:18)-(1:20); performing solid-liquid separation on the extraction material liquid obtained after flash extraction, and collecting a liquid phase so as to obtain a cannabidiol extract; performing alumina column chromatography separation on the cannabidiol extract so as to obtain an eluant; treating the eluant by using an organic nanofiltration membrane so as to obtain a membrane through liquid; and performing crystallizationtreatment on the membrane