Abstract: Flame-retardant polyurethane (TPUP) was synthesized from polyadipic acid 1,4 butanediol glycol(PBA), hexamethylene diisocyanate (HDI) and flame retardant N,N-bis(2-hydroxyethyl)aminomethylene phosphate diethyl phosphate (FCR6) as the main raw material. Flame-retardant polyurethane-based solid polymer electrolyte was prepared by mixing TPUP with LiTFSI and tested by infrared spectroscopy, thermogravimetric analysis, conical calorimetry, mechanical test, electrochemical window, ionic conductivity and charge-discharge performance test. The result showed that TPUP-based electrolyte TPUP25%Li possessed good mechanical strength (up to 2.09MPa) with a ionic conductivity of 3.09?10-4 S/cm at 80 ℃ . The discharge capacity of all-solid-state lithium battery assembled with flame retardant electrolyte reached 159mA?h/g at 0.2C at 80 ℃.