Abstract: Taking Asperg illus-type douchi as the research object, high-throughput sequencing technology was used to analyze the bacterial community structure composition and change rule of Aspergillus-type douchi in different fermentation stages. The results showed that the bacterial richness and diversity exhibited a trend of increasing followed by decreasing during fermentation. The bacterial diversity and richness reached the highest on the fifth day of fermentation. The predominant bacteria in the early fermentation period（Day0～Day5） are Acinetobacter, Myroides, Proteus and Klebsiella; however, the predominant bacteria in the middle and late ferm entation period（Day9～Day19） are Bacillus, which belong to the Firmicutes. The bacterial community structure and diversity of Aspergillus-type douchi were different in different fermentation stages. The bacterial community structure was similar among samples in the early fermentation stage, but similar in the middle and late fermentation stage. Through KEGG function prediction, it was found that the expression of metabolic function genes in the early stage of fermentation was significantly higher than that in the middle and late stages of fermentation, indicating that the microbial community was undergoing vital metabolic activities; the expression of functional genes in environmental information processing and genetic information processing in the middle and late fermentation were significantly higher than those in the early stage of fermentation, which may be caused by the harsh fermentation environment and the proliferation of bacteria of Firmicutes. This research can not only excavate the microorganisms closely related to the quality of douchi, but also provide a theoretical basis for explaining the production mechanism of Aspergillus-type douchi and improving the production process and further research.