Abstract： Lithium ionic conductivity of LISICON single crystals grown by Czochralski method has been investigated. It was found that the conductivities in different orientations do not show strong anisotropy and the relations between them are: σb≤σa≤σc≤σ. The lithium content in the crystals have obvious influence on conductivity. When Li/Zn ratio changes from 6.7 to 9.2, the conductivity in a-direction at 300℃ increases from 4.3 × 10-2Ω-1·cm-1 to 1.25×10-1Ω-1·cm-1. Three transition points at ～80℃, ～140℃ and ～300℃ have been shown in logσT vs. 1/T curves. The activation energy for conduction are 0.5-0.58 eV (25-80℃), 0.92 eV (80-140℃), 0.64 eV (140-300℃) and 0.36 eV (> 300℃) respectively. The polarization experiments indicated that LISICON is a lithium ionic conductor with negligible electronic conductivity.