Abstract: Disclosed is a method of preparing a solid electrolyte composition for a lithium secondary battery which includes: (a) mixing materials including Li2O, SiO2, TiO2, P2O5, BaO, Cs2O and V2O5; (b) melting the mixed materials; (c) rapidly cooling the molten materials at room temperature and compressing the molten materials using a preheated plate to form electrolyte glass having a predetermined thickness; (d) heating the electrolyte glass to eliminate stress at a predetermined temperature range; (e) heating the electrolyte glass to a higher temperature range higher than in the step of heating the electrolyte glass to eliminate stress to be crystallized; and (f) precisely adjusting a thickness of the electrolyte glass by lapping the electrolyte glass.