The 70Li(2)S center dot 30P(2)S(5) (mol%) glass was prepared by the melt quenching method and the glass-ceramic electrolytes were obtained by heating the prepared glass over crystallization temperatures. The superionic metastable Li7P3S11 crystal was formed by heating the glass in the temperature range from 280 and 360 degrees C. The conductivity of the glass-ceramics was enhanced by the precipitation and growth of the Li7P3S11 crystal, and the highest conductivity of 4.1 x 10(-3) S cm(-1) at room temperature was achieved in the glass-ceramic heated at 360 degrees C for 1 h. The Li7P3S11 crystal changed into the thermodynamically stable phase such as the Li4P2S6 crystal with further increasing heat treatment temperature and holding time, resulting in lowering conductivities of the glass-ceramics.