The present disclosure provides a blueberry fresh-keeping agent, preparation method and applications thereof, the fresh-keeping agent consisting of 0.03%-0.5% of a Galla chinensis extract, 0.5%-1.0% of ascorbic acid and 1.0%-2.0% of chitosan, and pH is 2.0-6.0. The fresh-keeping agent provided by the present disclosure may significantly inhibit blueberry Botrytis cinerea, effectively alleviate post-harvest blueberry membrane lipid peroxidation, maintain blueberry cell membrane completeness, and extend storage time of blueberries from 20 days in conventional cooling to 50 days, blueberry decay rate is reduced within 10%, and weight loss rate is controlled within 5%, achieving relatively long-term, high-quality fresh-keeping storage of blueberries. The blueberry fresh-keeping agent of the present disclosure is safe to use, and blueberries treated have no toxic and harmful substances, and have the characteristics of high efficiency, safety and environment-friendly.
