A method for preparing high-purity cannabidiol is characterized in that: the leaves of cannabis and top portions of the plant which account for about one-fifth of the whole plant are used as extraction sites; a technology of combined macroporous adsorption resin chromatography and polyamide chromatography is used for purification; and a mixed solvent system is used for crystallization purification so as to ensure that the yield is improved to the maximum extent under the premise of obtaining a high-purity product. The product obtained from this method contains high-purity CBD; the method has a high yield and is a simple process, and thus easy to industrialize.