In order to improve the antioxidant activity and flavor of snow pear juice,pear juice was fermented with Lac-tobacillus casei Y5-2b,Lactobacillus plantarum C17 and Lactobacillus acidophilus CH-2,respectively.Physicochemical properties and antioxidant activities were characterized.And high-performance liquid chromatography and gas chromatogra-phy-ion mobility spectrometry(GC-IMS)was applied to analyze the nutrients and aroma components.Results showed that the three strains had good growth and metabolism in pear juice.Moreover,the proliferation metabolism of Y5-2b and C17 showed better performance,with a stable number of viable bacteria reaching 9.0 lg CFU/mL at 20 hours.The antioxidant activity of fermented pear juice increased significantly(P<0.05).The sugar content decreased,with glucose being the most consumed and the utilization rate ranging from 5.29%to 8.85%.Partial organic acid content showed a decrease,with no malic acid detected in groups Y5-2b and C17.There was no significant difference in malic acid con-tent between the CH-2 group and the unfermented group(1 18 mg/100 mL),and the citric acid content decreased by 33.65%,42.97%,and 38.71%respectively after fermentation.Different lactic acid bacteria fermentation had different ef-fects on the content of phenols in pear juice,mainly arbutin,catechin and rutin.A total of 44 aroma components were identified from juice samples,of which 3-hydroxy-2-butanone,n-butyraldehyde,butyric acid and other characteristic flavor substances with fruit aroma increased in varying degrees after fermentation.In conclusion,lactic acid bacteria en-dowed the pear juice with abundant substances,flavor and high antioxidant activity,which provides a certain theoretical basis for lactic acid bacteria fermentation of pear juice.