The synthesis and transport properties of the Li6La3BiSnO12 solid electrolyte by a solid-state reaction were reported. The condition to synthesize the Li6La3BiSnO12 is 785 °C for 36 h in air. The refinedlattice constant of Li6La3BiSnO12is 13.007 ?. Qualitative phase analysis by X-ray powder diffraction patts combined with the Rietveld method reveals get type compounds as major phases. The Li-ion conductivity of the prepared Li6La3BiSnO12 is 0.85×10?4 S/cm at 22 °C, which is comparable with that of the Li5La3Bi2O12. The Li6La3BiSnO12compounds are chemically stable against LiCoO2 which is widely used as cathode material up to 700 °C but not against the LiMn2O4 if the temperature is higher than 550 °C. The Li6La3BiSnO12exhibitshigher chemical stability than Li5La3Bi2O12, which is due to Sn substitution for Bi.