The invention relates to the technical field of flax adsorbents, particularly a fermented flax adsorbent for white wine and a preparation method thereof. The fermented flax adsorbent for white wine is prepared from chopped flax fibers sequentially by Saccharomyces cerevisiae fermentation, Monascus Fulginosus fermentation, Lactobacillus plantarum fermentation, Pichia guilliermondii fermentation and drying. The preparation method of the fermented flax adsorbent comprises the following steps: preparation of chopped flax fiber fermentation liquor, Saccharomyces cerevisiae fermentation, Monascus Fulginosus fermentation, Lactobacillus plantarum fermentation, Pichia guilliermondii fermentation, drying and the like. The fermented flax adsorbent has obvious adsorption actions on methanol, isoamyl alcohol and isobutanol in wine, has the advantages of low total ester adsorption quantity for wine, simple preparation method, low preparation cost, high practicality and wide market prospects, and can easily implement industrial production.