Objective To explore the effect of sugar concentration on the flavor formation of Xiangxi radish pickles, in response to the "sugar reduction" demand for healthy diets.Methods Three sugar treatment groups are set up at the concentrations of 10%, 30%, and 50%. Then, the dynamic changes of metabolites and microbial community structure are systematically monitored during the fermentation process using gas chromatography-mass spectrometry (GC-MS) combined with 16S rRNA high-throughput sequencing.Results Levilactobacillus and Lactiplantibacillus are the dominant genera, with the highest abundance observed in the 10% sugar concentration group (P<0.05). In the later fermentation stage, the 30% sugar concentration group accumulates more alcohols, sugars, and organic acids, resulting in a more harmonious flavor profile. According to the partial least squares discriminant analysis (PLS-DA), 16 key metabolites are identified. Additionally, correlation analysis reveals that the two dominant genera are significantly associated with the metabolism of 9 and 12 flavor substances, respectively.Conclusion Moderate reduction of sugar concentration contributes to microbial community function and flavor substance synthesis.