Extracellular electron transfer (EET) is a process in which electrically-generated microorganisms transfer electrons to external electron acceptors during metabolism. However, the relatively slow rate of extracellular electron transfer significantly affects the electrical performance of Microbial fuel cells (MFCs). Improving the efficiency of extracellular electron transfer is of great significance for promoting the large-scale application of microbial fuel cells. Due to their excellent electrical conductivity, stability and biocompatibility, nanomaterials have been widely used to promote the extracellular electron transfer of microorganisms. This review summarizes the main routes of extracellular electron transfer, expounds the mechanism of different kinds of nano materials in promoting the process of extracellular electron transfer and the electrical properties of their corresponding MFCs, and looks forward to the research prospect of nano materials strengthening microbial EET process in the utilization of microbial electrochemical technology. Although there are still challenges to improve the electrical performance of microbial fuel cells, nanomaterials have great potential to promote the application of EET processes.