We successfully prepared the perovskite-type lanthanum lithium titanate (LLTO) ceramics electrolytes with high total lithium ion conductivity of 3–5 × 10−4 S cm−1 at 300 K. The high total conductivity is attributed to the elimination of resistive grain boundary by the grain growth. Using the electrolyte as a separator, a rechargeable aqueous-type lithium/air cell which composed of Li metal/Li organic electrolytes/LLTO ceramics tube/LiOH aq/O2 carbon electrodes was developed and the stable discharge/charge behaviors were confirmed. Owing to the low porosity and the stability to alkaline aqueous solution of LiOH as well as high ionic conductivity, the lithium ion-conducting lanthanum lithium titanate ceramics is suitable for an electrolyte separator for aqueous-type rechargeable lithium/air batteries.