Abstract: By high-throughput sequence methods, the research explored the diversity and succession of the bacterial communities in fermented grains of Shanxi aged vinegar. The results showed that during the acetic acid fermentation of Shanxi aged vinegar, mainly 7 phyla were at the phylum level, including Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes, among which the relative abundance of Firmicutes showed an increasing trend during the fermentation, and finally even reached over 98%, dominating the entire fermentation stage. At the genus level, the main bacteria participating in the acetic acid fermentation stage of Shanxi aged vinegar included Lactobacillus (57.4%~66.4%), Acetobacter (3.8%~27.3%), Streptococcus (0.3%~3.0%), Weissella (0.2%~1.8%), Bacillus (0.1%~1.2%), Pseudomonas (0%~1.8%), etc, among which Lactobacillus and Acetobacter bacteria dominated, with a relative abundance of around 90% in the first 5 days of fermentation. Meanwhile, Pseudomonas was not detected in the vinegar Pei samples during the early stage of the acetic acid fermentation, but appeared in the samples on the 5th day and reached its peak (1.1%~3.4%) on the 7th day. Besides, "mash inoculation" adopted during the acetic acid fermentation of Shanxi aged vinegar, the bacterial community structure as well as changes in different fermentation batches were basically the same, and the shared microbial species accounted for more than 70% of the total, indicating the stability of the solid-state fermentation process of Shanxi aged vinegar.