The invention relates to a plant beverage and a preparation method thereof. The plant beverage comprises edible plants and plant extracts, wherein the edible plants comprise at least three kinds of grapefruits, tomatoes, guavas, blueberries, cherries, blackberries, cranberries, rubus corchorifolius, aronia melanocarpa, sambucus williamsii fruits, Maqui berries and blackcurrants; and the plant extracts comprise at least one kind of a turmeric extract, a pepper extract, a grape seed extract, a coffee bean extract, a grapefruit extract, a tomato extract, a guava extract, a blueberry extract, a cherry extract, a blackberry extract, a cranberry extract, a rubus corchorifolius extract, an aronia melanocarpa extract, a sambucus williamsii fruit extract, a Maqui berry extract and a blackcurrant extract. The plant beverage disclosed by the invention contains rich phytochemicals capable of improving metabolic disturbance, and the phytochemicals have addition or synergistic reaction mutually; andplant fibers in fruits and vegetables are reserved, so that the plant beverage is beneficial to prevention of metabolic diseases and cardiovascular diseases, and is especially suitable for diabetes patients and diabetes high-risk groups to drink.