The invention discloses a preparation method of anisic acid, which comprises the following steps: taking a right amount of crude
sulfate turpentine, and fractionating to obtain crush
anethole; carrying out crystallizing separation on the
anethole to obtain the high-purity
anethole; adding the high-purity anethole and a NaHSO3 solution into a reaction kettle, and introducing
ozone to perform oxidation for 110 minutes, thereby obtaining an anisic
aldehyde sodium sulfite addition product A; simultaneously and slowly adding a
sodium hydroxide solution and oxydol into A, stirring to react for 5.0-9.0 hours while keeping at 65-85 DEG C to obtain a
reaction product B; and after the reaction is finished, adding a HCl solution into B to regulate the pH value to 1-3, and filtering to obtain the anisic acid. The method has the advantages of high yield and high purity and does not use any
organic solvent in the
separation process, so the product has no toxic or harmful
solvent residue and can be used in the industries of
medicine, food and
cosmetics; the method has the characteristics of mild
reaction conditions, simple purification and refinement and high product purity, and is simple to operate; and by using the
ozone and oxydol as oxidizers, the
reaction product is water, so the oxidizers are green and environment-friendly.