Perovskite materials have demonstrated excellent performance in the field of solar cells, and the device efficiency has already exceeded 25%. However, to date, perovskite solar cells (PSCs) have not been able to achieve large-scale production. The biggest obstacle to commercializing PSCs is the stability problem that has been widely criticized since their inception. In the last 5 years, the emergence of 2D/3D perovskites has provided a new way to solve this problem. In this review, the representative work on 2D/3D perovskites is summarized, focusing on how 2D/3D structures can simultaneously improve device efficiency and stability. Starting from materials, the current perovskite material system with 2D/3D structure, as well as the bulky organic molecules used to prepare 2D/3D perovskites, is summarized and the corresponding preparation methods are discussed. After that, the influence of the 2D/3D structure on the crystallization of perovskites, the passivation, stabilization, and protection of 2D perovskite on 3D perovskite, and the mechanism of the 2D/3D perovskite heterojunction are discussed in depth. In the end, the development of 2D/3D perovskite from the aspects of research status, advantages, problems encountered, and future research directions is analyzed and prospected.