With the Lonicera caerulea L. juice as the raw material, the work aims to select the lactobacillus acidophilus to reduce the acidity of fruit juice by fermentation, in order to improve the juice taste. Taking the acid reduction rate of juice as the index, the technological conditions were optimized by single factor and orthogonal experiment, and the changes of the main organic acid content in the juice before and after acid reduction and the juice related indexes were measured. The optimum conditions obtained for acid reduction were as follows: fermentation temperature of 34 ℃, inoculation volume of 2.5×107 CFU/mL, initial pH 3.4, additive amount (mass fraction) of glucose of 3%, and additive amount (mass fraction) of tryptone of 3%. Under these conditions, the acid reduction rate of juice was 86.32%, the malic acid and citric acid measured by HPLC in the juice were respectively decreased by 49.37% and 36.05%, and the indexes of anthocyanin and reducing sugar were slightly decreased. Lactobacillus acidophilus can be effectively used in acid reduction treatment of Lonicera caerulea L. juice, which helps improve the taste of juice.