Syntrophic interaction occurs during anaerobic fermentation of organic substances forming methane as the final product. H2 and formate are known to serve as the electron carriers in this process. Recently it has been shown that direct interspecies electron transfer (DIET) occurs for syntrophic CH4 production from ethanol and acetate. Here we constructed paddy soil enrichments to determine the involvement of DIET in syntrophic butyrate oxidation and CH4 production. The results showed that CH4 production was significantly accelerated in the presence of nanoFe3O4 in all continuous transfers. This acceleration increased with the increase of nanoFe3O4 concentration but was dismissed when Fe3O4 was coated with silica that insulated the mineral from electrical conduction. NanoFe3O4 particles were found closely attached to the cell surfaces of different morphology, thus bridging cell connections. Molecular approaches including DNA-based stable isotope probing revealed that the bacterial Syntrophomonadaceae and Geobacteraceae, and the archaeal Methanosarcinaceae, Methanocellales and Methanobacteriales were involved in the syntrophic butyrate oxidation and CH4 production. Among them, the growth of Geobacteraceae strictly relied on the presence of nanoFe3O4 and its electrical conductivity in particular. Other organisms except Methanobacteriales were present in enrichments regardless of nanoFe3O4 amendment. Collectively, our study demonstrated that the nanoFe3O4-facilitated DIET occurred in syntrophic CH4 production from butyrate and Geobacter species played the key role in this process in the paddy soil enrichments.