Abstract: Plum juice was used as material and Oenococcus oeni was used as strain for malolactic fermentation (MLF) to reduce acids in juice. The results were as follows:when the inoculation amount was 2.0×108CFU/mL, the pH was equal or greater than 3.4, the MLF proceeded normally and the acidity of plum juice was reduced by more than 61.35%. When the inoculation amount was 2.6 ×107CFU/mL and the pH was 3.6, the MLF could perform and the acidity of plum juice was reduced by 77.60%. When the inoculation amount was 2.3×108CFU/mL and the pH were 3.6 and 4.0, compared with the sample without adding glucose, the acidity of plum juice reduced by 27.04% and 34.63% respectively with 1.0g/100g glucose. In sodium citrates buffer system, the acidity reduced by 26.40%, it was proved that Oenococcus oeni could use citric acid as carbon resource to run of MLF.