To study the effects of microbial growth and metabolism on the texture and quality of sourdough fermented steamed bread， high-throughput sequencing was used to compare sourdough fermented wheat (SW) /wheat-millet (SM) doughs， and the physical characteristics of wheat/wheat-millet steamed bread and its correlation with microorganisms were analyzed. The results showed that there were some differences in microbial diversity and richness between the two groups， but the differences were not significant. The diversity of bacterial and fungal communities in SM was low. Fungi had higher richness than bacteria， but lower diversity. The microbial flora composition of the two groups was similar. The dominant bacterial genera were Lactobacillus and Pediococcus and the dominant bacterial species were Lactobacillus crustorum and Lactobacillus fermentum. They were all significantly different in SW and SM(P<0.05). The dominant fungal genus was Saccharomyces， which was composed of Saccharomyces cerevisiae. KEGG analysis showed that secondary metabolite biosynthesis and amino acid metabolism were highly metabolized pathways in SM， while carbohydrate， lipid， vitamin and nucleotide metabolism were significantly up-regulated in SW (P<0.05). Compared with wheat steamed bread， the wheat-millet steamed bread had higher hardness， specific volume and chewiness， but lower springiness and cohesiveness. Lactic acid bacteria could improve the texture of steamed bread， depending on the species of bacteria. There was a significant positive correlation between low abundance genera and springiness (P<0.05). These results provided a theoretical basis for exploring the formation mechanism of microbial composition and physical characteristics， and a reference for screening potential microorganisms to improve the quality of sourdough fermented steamed bread.