The degradation in the organic acid levels and aroma-producing characteristics of Lactobacillus fermentum strains during the fermentation of Choerospondias axillaris juice remain unknown; thus, high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) were employed to measure such changes before and after fermentation. The results showed significant reductions in the citrate (from 4.91 g•L-1 to 0.90 g•L-1) and malate (from 4.94 g•L-1 to 4.61 g•L-1) contents of the juice following fermentation with L. fermentum, and a considerable amount of lactic acid (approximately 6.18 g•L-1) and small amount of acetic acid (approximately 0.18 g•L-1) were produced during the fermentation process. Aroma compounds such as ethyl acetate, 2-octanone, ethyl benzoate, linalool, and geraniol, which were generated during fermentation, enhanced the grassy, citrusy, and rosy floral-fruit aromas of the C. axillaris juice, resulting in a rich and mellow aroma profile, with multivariate statistical analysis indicating six differential volatile aroma components in the L. fermentum-fermented C. axillaris juice. The findings thus suggest that L. fermentum degrades citrate and malate, as well as exhibiting strong aroma-producing capabilities during fermentation. The results of this study are expected to provide key approaches for improving the quality of Lactobacillus-fermented fruit juices and developing new products.