The prepolymers of polyether urethane acrylate (PEUA) were synthesized from polyether polyol (polyethylene glycol (PEG) or polypropylene glycol (PPG)), diisocyanate (hexamethylene diisocyanate (HMDI) or toluene 2,4-diisocyanate (TDI)), and the caprolactone-modified hydroxyethyl acrylate (FA2D) using the catalyst (dibutyltin dilaurate (DBTDL)) by stepwise addition reaction. Lithium triflate (LiCF3SO3) was dissolved in PEUA prepolymers, and plasticizer (propylene carbonate (PC)) was added into prepolymer and salt mixtures. Then photoinitiator (Irgacure 184) was also dissolved in the mixtures. Thin films were prepared by casting on the glass plate, and then by curing the plasticized prepolymer and salt mixtures under UV radiation. Electrochemical and electrical properties of PEUA-LiCF3SO3-based polymer electrolytes were evaluated and discussed to be used in lithium batteries.