The invention provides an Antrodia fermented product and a preparation method thereof. The preparation method comprises the following steps that (1) Antrodia is soaked in water, extracted, crushed and subjected to mashing, and mash is obtained; (2) after culture medium components are added into the mash, leuconostoc mesenteroides are added to carry out first fermentation, and first fermentation liquor is obtained; (3) pectinase is added into fruit and vegetable liquid with the pH value being 4.5-6 to carry out enzymolysis, and zymolytic fruit and vegetable liquid is obtained; (4) after culture medium components are added into the zymolytic fruit and vegetable liquid, compound lactic acid bacteria are added to carry out second fermentation, and second fermentation liquor is obtained; (5) after culture medium components are added into the second fermentation liquor, compound microzyme is added to carry out third fermentation, and third fermentation liquor is obtained; (6) the first fermentation liquor and the third fermentation liquor are evenly mixed and then centrifuged, and the Antrodia fermented product is obtained after homogenization and sterilization are carried out on centrifuged supernate. The Antrodia fermented product is good in taste and unique in flavor, has good immune adjustment and oxidation resistance functions, and is suitable for the crowd.