Preparation method of ellagic acid

The invention discloses a preparation method of ellagic acid, which comprises the following steps: repeatedly mixing a tannic acid alkaline solution with air under the action of a jet pump, carrying out oxidation treatment to prepare ellagic acid, and carrying out purification and refining treatment on an ellagic acid crude product prepared by oxidation treatment to obtain high-purity refined ellagic acid. The ellagic acid prepared through the method is high in yield and purity, the thermal stability of the ellagic acid is improved, the method prepares the ellagic acid by combining a liquid-gas jet oxidation method and a solvent washing method, the preparation time of the ellagic acid is greatly shortened, the purity of the ellagic acid is obviously improved, the production efficiency of industrial production of the ellagic acid is obviously improved, and the method is suitable for industrial production of the ellagic acid. The method is suitable for industrial large-scale production of ellagic acid, and wide