The purpose of this study was to investigate the anaerobic digestion (AD) of rice straw at different temperatures in a 300 m(3) bioreactor. The results showed that the biogas yield was 401.9 m(3)/ton (dry straw weight) in this AD system. The contents of total solids, volatile solids, chemical oxygen demand, pH, NH4+-N, and volatile fatty acids were all in the optimal range, indicating that the entire AD system was stable and efficient. In addition, the phylum Bacteroidetes was the main type of bacteria found during the AD process. When the temperature increased, the relative abundance ratio of Methanoculleus, Methanosarcina, and Firmicutes increased. The phyla Bacteroidetes and Fibrobacteres predominated in straw samples, and the relative abundance ratio of Firmicutes and Bacteroidetes in thermophilic AD was much greater than that in mesophilic AD. This study provides new evidence regarding the effects of temperature on the community changes of specific microbiota in the AD of rice straw.