The invention relates to daidzein micelles and a preparation method thereof. The daidzein micelles contain 1 part of daidzein, 12 to 30 parts of phospholipid and 1 to 25 parts of additive. The preparation method comprises: preparing a daidzein and phospholipid composite, namely, adding daidzein and 50 to 95 percent of phospholipid into an organic solvent, heating the solution to 40 to 60 DEG C, refluxing under reduced pressure, keeping temperature and stirring for 2 to 10 hours, recovering the organic solvent, drying and crushing to obtain the daidzein and phospholipid composite; and preparing daidzein micelles from the phospholipid composite, namely, dissolving the daidzein and phospholipid composite, the rest phospholipid and the additive in an organic solvent, subjecting the solution to rotary evaporation to form a film, and hydrating at 40 to 60 DEG C to obtain daidzein micelle suspension with opalescence. The average particle size of the daidzein micelles is less than 50 nanometers. The daidzein micelles can be further prepared into oral or injection preparations including capsules, oral mixed suspension, oral liquid, injection, injection freeze-dried powder injection.