At present, replacing traditional electrolytes with solid electrolytes to develop new all-solid-state lithium ion batteries has become an important technical method to solve the battery safety problems and improve the battery energy density. As the core material of all-solid-state lithium ion batteries, the performance of the solid electrolyte largely determines the performance of the battery. So far, many inorganic solid electrolyte materials have been studied, including crystalline solid electrolyte such as NASICON-type, LISICON-type, perovskite-type and garnet-type and other glassy solid electrolyte such as oxide and sulfide. Among them, the garnet-type Li7La3Zr2O12 has excellent comprehensively electrochemical performance, which promises it a more practical application potential and more research value. Experiments and theoretical calculations show that this material has a high lithium ion conductivity (10-4 ~ 10-3S·cm-1), and can contact with the negative metal lithium and most of the cathode material in a more stable state, and its electrochemical window is as wide as 6V. In this paper, we will introduce the crystal structure, preparation method and doping modification of Li7La3Zr2O12 in detail basing on the research status at home and abroad in recent years, and then expound the development prospects and challenges of Li7La3Zr2O12 as a solid electrolyte applying in all-solid-state lithium ion batteries.