A solid-liquid composite method (SLM) of Al-substituted cubic lithium lanthanum zirconium garnet (c-LLZO) was developed. Cubic LLZO powders whose composition was Li6.23Al0.26La3Zr1.88O11.76 were prepared from the stoichiometric mixtures of lithium acetate, lanthanum oxide, zirconia and alumina, followed by an annealing of the dried precursor at 750 degrees C for 12 h in an air atmosphere. The resultant powders were characterized by XRD, SEM and ICP-OES. The conventional solid-state reaction methods using carbonates and hydroxides as lithium sources are also simply introduced as a comparison. In addition, the phase formation of c-LLZO powders synthesized by the ZrO2 powders with different specific surfaces as raw material was also investigated. The results show that the cubic garnet phase LLZO powders was obtained when the value of the specific surface area (SSA) of the material ZrO2 powder was about 110 m(2) g(-1) . Sintering these cubic phase powders at 1150 degrees C for 6 h in air after uniaxial pressing obtained a dense ceramic pellet with a relative density of 91.2% and ionic conductivity of 2.54 x 10(-4) S cm(-1) at 23 degrees C.