A cross-linked polymer electrolyte membrane (SPE) was fabricated by a solvent-free hot-pressing method for all-solid-state lithium ion battery. The ionic conductivity of the electrolyte is 1.34 × 10−3 S cm−1 and the decomposition potential is 4.87 V at the ethylene oxide (EO):LiN(SO2CF3)2 (LiTFSI) molar ratio of 20:1 and 120 °C. TG-DSC results show that the SPE is thermally stable up to 230 °C in argon atmosphere. The assembled LiFePO4/SPE/Li all-solid-state battery can stably work in the temperature range of 80–140 °C. At 120 °C, the initial discharge capacity of the battery is 156.7 mAh g−1 at 1C which is close to the theoretical capacity of the cathode material, showing that the solvent-free filming method is low-cost and environment-friendly for solid polymer electrolyte and all-solid-state lithium ion battery.