Preparation method for fermented beverage

The invention belongs to the technical field of beverage preparation, and particularly relates to a preparation method for a fermented beverage. The preparation method comprises a saccharification process and a fermentation process, and particularly comprises the following steps: firstly, carrying out gelatinization of oats and coix seeds in water, then carrying out saccharification and heat preservation of the gelatinization liquid of the oats and the coix seeds, barley malt, water, amylase and protease, after filtering the saccharification liquid, boiling, standing, discharging a precipitation, cooling, and adding yeasts and lactic acid bacteria for mixed fermentation. A fermentation liquid culture medium is prepared by utilizing the coix seeds having relatively high nutritional value and the oats having the functions of invigorating stomach and aiding digestion as auxiliary materials and utilizing barley as a main material, so that the final product has the functions of invigorating stomach and aiding digestion while having high nutritional value. The yeasts and the lactic acid bacteria are employed for one-time mixed fermentation, thus the production time is shortened, the production efficiency is improved, and the product flavor is increased.