Abstract:Auricularia auricula is rich in nutrition and contains various active ingredients. Many macromolecular substances in Auricularia auricula cannot be absorbed or utilized by the human body. Fermentation can decompose macromolecular nutrients into components of smaller molecules that are more easily absorbed. In this study，Auricularia auricula was taken as the raw material，which was fermented by Lactobacillus acidophilus.Then，with sensory score as the index，the response surface method was used to optimize the fermentation process of Lactobacillus acidophilus based on the single factor experiment. Additionally，the content of organic acids，polysaccharides，and proteins in the fermented Auricularia auricula beverage was analyzed by methods such as liquid chromatography，the anthrone-sulfuric acid method，and the coomassie brilliant blue method.The optimal technological conditions for Auricularia auricula beverage fermented by Lactobacillus acidophilus were determined as follows：a liquid-solid ratio of 80∶1 （mL/g），a starter inoculation amount of 1.5%，a fructooligosaccharide addition amount of 2.0%，and a fermentation time of 24 h. Under these conditions，the total acid content was 5.62 g/kg，the polysaccharide content was 6.85 g/L，and the protein content was 2.65 g/L. Oxalic acid was the only organic acid that could be detected in the unfermented Auricularia auricula beverage，while four kinds of organic acids，mainly lactic acid and succinic acid，could be detected in the beverage fermented by Lactobacillus acidophilus. During the fermentation process，lactic acid，succinic acid，and citric acid were produced，while the oxalic acid content was increased.