Polycarbonate polyurethane (PCPU) with 30% hard segment was synthesized from isophoronediisocyanate, polycarbonate diol and diethylene glycol. Solid polymer electrolytes (SPE) with various concentration of lithium salts were prepared by the complexing of polyurethane and Lithium bistrifluoromethane sulfonyl imide(LiTFSI). The structure of polyurethane was analyzed by infrared spectroscopy. The thermal properties of polyurethane and electrolyte were tested by TG and DSC. The effects of different LiTFSI contents on the electrochemical properties of electrolyte were investigated by AC impedance and linear sweep voltammetry.The results indicated that the ionic conductivity of PU-based solid polymer electrolytes at room temperature increase with the increase of LiTFSI content then decrease and then increase. The ionic conductivity of the solid polymer electrolytes with 70% lithium salt concentration reached the maximum value among the as-prepared electrolytes, the all-solid-state battery using the PU-based electrolytes and LiFePO4 delivered the discharge capacity of 153 mA·h/g at 0.2C at 60°C, and the capacity retention reached 84% after 100 cycles.