Abstract: To obtain lactic acid bacteria with aroma-producing capabilities for application in mustard fermentation, traditional isolation and culturing methods were employed to screen presumptive LAB strains from fermented vegetables. Aroma-producing LAB were selected using sniffing test and diacetyl content analysis. Growth and fermentation characteristics of the strains were studied, and they were inoculated into mustard juice to analyze volatile aroma components. The results showed that: A total of 67 LAB strains were isolated, from which 5 aroma-producing strains were screened. Based on morphological, physiological, biochemical, and 16S rDNA molecular identification, strains LJ036, LJ065, QT038, and JC091 were identified as Lactiplantibacillus plantarum, while JC045 was identified as Weissella hellenica. LJ065 and QT038 exhibited stronger acid-producing capabilities. QT038 grew well at pH 3.5, showed slightly higher salt tolerance, and demonstrated good temperature tolerance. LJ036 exhibited the strongest antibacterial effect against Staphylococcus aureus. LJ065 possessed the highest nitrite degradation ability, with a degradation rate of 94.45%. HS-SPME-GC-MS (Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry) identified 52 volatile compounds. The fermented groups contained higher levels of alcohols, aldehydes, and ketones. Among them, the QT038, LJ065, and LJ036 fermentation groups showed higher diacetyl contents of 4.27, 3.11, and 3.80 μg/mL, respectively. Cluster heatmap analysis revealed higher levels of volatile components such as (Z)-2-hexen-1-ol, damascenone, (Z)-3-hexen-1-ol, 2-ethylphenol, and linalyl acetate in QT038, LJ065, and LJ036 fermented mustard juice, imparting more intense floral, fruity, and herbaceous notes to the mustard greens. Comprehensive evaluation indicated that QT038, LJ065, and LJ036 possess favorable fermentation and aroma-producing characteristics and show promise as potential starter cultures for inoculated fermentation of mustard.