This study was conducted to explore the necessity, functionality, and small-scale fermentation performance of ten core microbial species in the synthetic microbial community for Xiaoqu light-flavor Baijiu. The necessity and functionality of the core species were determined based on the effects of single-species omission experiments on fermentation parameters and volatile flavor compounds in the final distillate. The community composition was subsequently optimized accordingly. Finally, the production performance of the optimized synthetic community was assessed in a 20 kg fermentation system. The omission experiments confirmed that all ten species were essential functional microbiota, as the absence of any single species led to deviations in physicochemical parameters and flavor profiles from those of the traditional Qu starter. Moreover, the 2,3 butanediol content in the Baijiu sample produced with the synthetic community was significantly higher than that of the original Qu group. Based on the negative correlation between 2,3 butanediol synthesis and the core species, the 2,3 butanediol level in the synthetic community sample was successfully restored to match that of the original Qu group by doubling the inoculation ratio of Saccharomyces cerevisiae within the community. In the 20 kg scale fermentation, no significant difference was observed in 2,3 butanediol content between the optimized synthetic community group (5.77 mg·L?¹) and the original Qu group (6.18 mg·L?¹). Both Baijiu samples exhibited typical sensory characteristics of Xiaoqu light-flavor Baijiu, and the sensory evaluation scores showed no significant difference between them. These findings will provide theoretical guidance for the development and application of synthetic microbial communities in other light-flavor Baijiu production processes.