The invention discloses an asparagus beverage and a preparation method thereof. The preparation method comprises the following steps: juicing, performing high-temperature autoclaved sterilization, performing lactobacillus fermentation, performing saccharomycetes fermentation, performing bacillus aceticus fermentation, mixing instant coffee and a final fermentation product, and filling. The method has the beneficial effects that the asparagus juice is subjected to lactobacillus fermentation and lactic acid with soft sour is generated, wild wormwood flavor in the asparagus is removed through the saccharomycetes fermentation, fermentation aroma is generated, and finally, acetic acid aroma is generated through the bacillus aceticus fermentation; the asparagus fermented beverage prepared by the method is golden yellow in color, clarified and transparent and unique in flavor, does not contain an additive, contains rich proteins, amino acids, vitamins, lactic acid and other nutritional ingredients and has the health-care effects of appetizing, tonifying spleen, reducing blood pressure, allaying tiredness and the like; moreover, according to the asparagus and coffee mixed beverage, various original nutritional ingredients of the asparagus and elegant asparagus aroma are kept, and the bitter taste of coffee is changed.