The invention discloses an antrodia camphorata functional beverage and a preparation method thereof. The beverage is a beverage which is rich in nutrient substances including amino acid and the like and various active substances such as antrodia camphorata and is prepared by washing red dates, denucleating the washed red dates, baking and crushing, and carrying out deep antrodia camphorata fermentation with red data powder. The beverage contains the active substances and the various nutrient substances including triterpene, polysaccharide and the like and has a very good liver protection effect.