Abstract: Abstract: In this study, 16S rRNA gene high-throughput sequencing technology was used to elucidate bacterial community structure during short-term and long-term fermented litter. The correlation between the bacterial community structure and carbon, nitrogen composition of the mattress for pig raising was analyzed. The results showed that the dominant bacteria in the microbial fermentation bed were Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes etc.. Moheibacter, and Clostridium were the most abundant genus in fermentation litter. The diversity of bacterial community and principal component analysis of samples in fermentation bed showed that the cultivation time affected the diversity and composition of microbial community to a certain extent, but the difference was not significant. With the prolongation of culture time, the relative abundance of Actinobacteria and Cholroflexi respectively increased from 21.3% and 1.64% to 28.4% and 4.34% at the phylum level significantly(P<0.05). At the genus level, the relative abundance of eleven species, including Methylocaldum, Methylobacter, Actinomadura, Mycobacterium, Rhodococcus, Paracoccus increased significantly. Also the relative abundance of Methylocaldum and Actinomadura increased from 0.405%、0.570% to 2.862% and 2.19% respectively. But for Pseudomona, Psychrobacter, Sphingobacterium, Flavobacterium and other species were decreased significantly, and the relative abundance of Pseudomonas and Psychrobacter decreased from 2.51% and 2.13% to 0.93% and 0.18% respectively. Nitrate nitrogen content increased significantly, while organic matter, cellulose and lignin content decreased significantly. Mantel test analysis showed that it was positively correlated with significance at P<0.05 between bacterial community and cellulose content (r=0.333). Spearman correlation analysis showed that Acinetobacter and Pseudomonas were positively correlated with cellulose, hemicellulose and lignin contents, while Gelidibacter and Pseudomonas were positively correlated with cellulose contents. Cellulose was an important factor affecting bacterial community in microbial fermentation bed. This study could provide a reference for choosing the appropriate proportion of the mattress and different mattress in the preparation period of fermentation bed, and improved the conversion efficiency of pig manure.