High-quality Li3PO4 thin film was prepared by PLD technique as a solid electrolyte of thin film battery. The structure, ionic conductivity and electrochemical stability of the film were characterized. Ionic conductivity of the film was 4.5×10-7 Scm-1 at 25°C with activation energy of 0.6 eV. The stability window of the film was range from 0 to 4.7 V vs. Li/Li+. Thin film battery Li/Li 3PO4/LiCoO2 shows electrochemical charge/discharge peaks due to the intercalation of LiCoO2. Excellent stability and cycle performance was demonstrated.