Preparation method of whole grain clear juice beverage low in calories, balanced in nutrients, smooth and refreshing in mouthfeel and difficult to precipitate

The invention discloses a preparation method of a whole grain clear juice beverage low in calories, balanced in nutrients, smooth and refreshing in mouthfeel and difficult to precipitate. The clear juice beverage is prepared by the following steps: mixing black rice, glutinous rice, millet, Chinese yams, red beans, white kidney beans, lotus seeds, taros and coix seeds to obtain a mixed raw material, and performing steam boiling, pectinase enzymolysis, cellulase enzymolysis, compound amylase enzymolysis, compound protease enzymolysis, compound clarification with chitosan and bentonite, flavoring and the like on the mixed raw material. The beverage prepared by the method disclosed by the invention contains rich multiple proteins, B group vitamins, vitamin E, carotenes, hydrochloric acid, riboflavin, anthocyanin, dioscin, coixenolide and coixol, various elements including calcium, phosphorus, potassium, magnesium, iron and zinc are proper in coordination of content, the nutrients are balanced and easy for a huma