Abstract: Batch experiments was conducted to investigate the effects of cow manure strains inoculation on fermentation characteristics of rice straw and solid-liquid phase flora. The results showed that two methane-producing peaks appeared on the 4th and 38th day respectively in the inoculation system of cow manure strains. The methane productivity from rice straw reached to 269.32 mL/g（measured by VS ）， which was 35% higher than the control system. The activity of cellulase and xylanase reached 18.82 U/mL and 214.55 U/mL， respectively， which made the quality degradation rate of dry base reached 41.79%. After fermentation， the structure of bacteria and methane bacteria changed significantly， the relative abundance of cellulose hydrolyzed bacteria such as Ruminococcus and Fibrobacter in solid phase of rice straw increased， and co-metabolites with Methanobrevibacter and Methanosarcina， respectively， which was the key to the efficient hydrolysis of rice straw to produce methane in the inoculation system of cow manure strains. It was different from the Syntrophobacter and Pelotomaculum existed in the control system， Aminobacterium and Syntrophomonas in the inoculation system reduced propionic and butyric acid concentrations， and the methane-producing pathway of eosinophilic acid was dominant， which improved the efficiency of anaerobic fermentation.