Abstract: Over the past decade, the power conversion efficiency of perovskite solar cells has increased from 3.8% to the current 25.5%, which is expected to become the next generation of commercial thin-film solar cells. However, the widely used TiO2 electron transport layers currently face challenges in device performance, especially long-term stability, due to its low electron mobility, high annealing temperature, and poor UV light stability. SnO2 is expected to be the first choice to replace TiO2 electron transport layers because of its high electron mobility, suitable band structure, low-temperature solution synthesis and stable chemical structure. At present, the interface optimization of SnO2/perovskite film to improve cell efficiency and stability has triggered a research boom. Therefore, it is very important to understand, control and optimize the interface structures of SnO2 and perovskite film. In this paper, the types and characteristics of defects in the bulk and surface of the SnO2 electron transport layer, as well as defects in bulk, grain boundaries and surface of the perovskite film are firstly introduced. The research progress of the interface modification and performance improvement for SnO2 electron transport layer/perovskite, perovskite/hole transport layer are reviewed in detail. Finally, the research directions of SnO2-based perovskite solar cells on interface modification and performance optimization are summarized and prospected.