A method for preparing dihydromyricetin nanocrystals includes: uniformly dispersing dihydromyricetin in a good solvent to obtain a dihydromyricetin solution; uniformly dispersing a precipitator and a stabilizer in water to obtain a mixed solution, and then adding the dihydromyricetin solution into the mixed solution and mixing uniformly under a stirring condition to obtain a dihydromyricetin nanocrystal solution; and drying the dihydromyricetin nanocrystal solution to obtain the dihydromyricetin nanocrystals. The method for preparing the dihydromyricetin nanocrystals by an anti-solvent method is simple and easy to implement, low in cost, good in nanocrystal stability, small in organic solvent consumption, and safe and environment-friendly in preparation process.