Novel glass-ceramics solid electrolytes were prepared from mechanically milled glassy powders in the ternary system Li2S-SiS2-P2S5. With an increase in the heat-treatment temperature, an ambient temperature conductivity of the obtained glass-ceramics reached 1.2x10(-3) S cm(-1), which is higher than the maximum conductivity of the solid solutions in the system Li4SiS4-Li3PS4. The enhancement on conductivity by heat-treatment over the crystallization temperature is due to the formation of the highly conductive crystalline phase with the same superlattice structure as the thio-LISICON phase of Li4-xGe1-xPxS4 (0.6