Solid state glass electrolyte, xLi2O-(1− x)(yB2O3-(1− y)P2O5) glasses were prepared with wide range of composition, i.e. x =0.35–0.5 and y =0.17–0.67. This material system is one of the parent compositions for chemically and electrochemically stable solid-state electrolyte applicable to thin film battery. Lithium ion conductivity of Li2O–B2O3–P2O5 glasses was studied in the correlation to the structural variation of glass network by using FTIR and Raman spectroscopy. The measured ionic conductivity of the electrolyte at room temperature increased with x and y. The maximum conductivity of this glass system was 1.6×10−7 Ω−1 cm−1 for 0.45Li2O–0.275B2O3–0.275P2O5 at room temperature. It was shown that the addition of P2O5 reduces the tendency of devitrification and increases the maximum amount of Li2O added into glass former without devitrification. As Li2O and B2O3 contents increased, the conductivity of glass electrolyte increased due to the increase of three-coordinated [BO3] with a non-bridging oxygen (NBO).