Methane is a crucial green-house gas as well as a typical renewable biomass energy. About 70% of the current CH4 emission into the atmosphere is originated from methanogenic microbial processes. In methanogenic environments, the close coupling of methanogens with syntrophic bacteria overcomes the energetic barriers for the anaerobic oxidation of short-chain fatty acids and alcohols with CH4 and CO2 as end products. Interspecies electron transfer is a critical step of this process. Here we firstly overviewed the research significance of methane and the microbial processes of syntrophic methanogenesis by degrading organic matters. And secondly summarized the origins, developments, research status and questions to be solved of the three interspecies electron transfer mechanisms, which is interspecies hydrogen transfer (IHT), interspecies formate transfer (IFT) and direct interspecies electron transfer (DIET).