With the increasing demand for storage devices with higher energy output and better safety performance, all-solid-state batteries show their potential to replace the traditional liquid-based Li-ion batteries in the future storage market. Garnet-type Li₇La₃Zr₂O₁₂ is one of the most attractive solid electrolyte materials because of its high ionic conductivity and stability to lithium metal. However, the large interfacial resistance originating from the insufficient solid-solid contact and the penetration of the lithium dendrite due to the inhomogeneous dissolution and deposition of lithium, hinder the all-solid-state batteries from developing. Focusing on the main interfacial problems in garnet-type all-solid battery, this review provides a fundamental understanding of the Li₂CO₃ issues in Li₇La₃Zr₂O₁₂ solid electrolyte and addresses the key factors influencing Li/ Li₇La₃Zr₂O₁₂/cathode interfacial wettability and the growth of Li dendrite, thus giving the key factors of constructing ideal interfaces. Finally, the possible research direction of garnet-type all-solid-state battery in the future is also prospected, which provides a guidance for developing and using all-solid-state batteries.