Abstract: In recent years, perovskite solar cells have developed rapidly. The electron transport layer plays an important role in transmitting electrons and blocking holes, which is the guarantee for improving the efficiency of perovskite solar cells. Starting from the working mechanism of the electron transport layer, this review introduces the research progress of metal oxides and organic molecular materials as electron transport materials, and expounds some modification works of the electron transport layer, such as ion doping, interface modification and nanostructure adjustment. Finally, the future research trend of electron transport layer is prospected.