The present study determined the dynamic changes of bacterial community structures and its metabolism functions in rice straw composting process with different types of biochar addition. Results showed that both wheat and maize straw biochar addition greatly increased the temperatures and germination index. Biochar addition influenced microbial community structure and metabolic characteristics of the compost. Firmicutes, Actinobacteria and Proteobacteria were the dominant phyla throughout the process, and both biochar addition significantly increased the relative abundance of Actinobacteria phylum, especially genus Saccharomonospora. The abundance of bacterial genes related to amino acid metabolism, carbohydrate metabolism and energy metabolism were also increased with biochar addition. Moreover, total nitrogen was strongly affected by biochar addition and had the greatest influence on the bacterial community structure. These results indicated that biochar addition improved the maturity and fertility of the compost product as well as significantly regulated the microbial community structure and functions during composting process.