By analyzing the changes of Saccharomyces cerevisiae fortification on the microbial composition and volatile metabolites of Nong-flavour fermented grains， the disturbances of the microbial ecological network， volatile metabolites and the potential metabolic functions of the microbial community were explored. A strain of Saccharomyces cerevisiae Y1 isolated from nong-flavour fermented grains fermented was used to disturb the solid-state fermentation of fermented grains， and the composition of microorganisms and volatile metabolites were studied by high-throughput sequencing technology and headspace solid-phase microextraction-mass spectrometry technology， respectively. The random forest learning algorithm was used to calculate the biomarkers between the experimental group and the blank group， and the differences in the microbial ecological network between the experimental group and the blank group were analyzed based on the construction of a co-occurrence network model. PLS-DA analysis and Spearman correlation were used to analyze the differences of volatile flavor compounds， the correlation of differential metabolites and biomarkers， respectively. Finally， potential functional changes were analyzed by PICRUST2 functional prediction and pathway enrichment. The results showed that 5 bacteria and 15 fungi can be used as biomarkers to characterize the microbial composition of fermented grains disturbed by Saccharomyces cerevisiae， and also increased the complexity of the microbial ecological network. Meanwhile， the composition of volatile metabolites was altered， with 18 differential metabolites， and the content of some volatile metabolites was improved. The vast majority of biomarkers were significantly associated with differential metabolism. In addition， the perturbation effect of Saccharomyces cerevisiae resulted in 180 up-regulated genes and 46 down-regulated genes in the microbial community， most of which were related to the metabolism of substances. These results provide a basis for the application of Saccharomyces cerevisiae in Baijiu fermentation and the optimization of the fermentation process of fermented grains.