NOVELTY - Polymer film prepared by copolymerization of acrylonitrile monomer and butyl methacrylate monomer to obtain copolymers Aa and Ab, adding copolymer Aa and Ab into nanoparticle dispersed in organic solvent to form mixed solutions of Ba and Bb, respectively, spraying the mixed solutions of Ba and Bb using electrostatic spinning machine, then carrying out electrostatic spinning process with mixed solutions flow rate of 0.4 ml/minutes, increasing or decreasing the flow rate at a constant amplitude, carrying out annealing treatment after spinning process, and then drying, is claimed.    USE - The polymer film is useful in gel polymer electrolyte, which is useful for lithium ion polymer battery (all claimed).    ADVANTAGE - The polymer film has good mechanical property, porosity and thermal stability, and high liquid absorption rate. The gel polymer electrolyte has high ionic conductivity and voltage resistant. The high secure lithium ion polymer battery has good charging and discharging performance.    DETAILED DESCRIPTION - Polymer film prepared by copolymerization of acrylonitrile monomer and butyl methacrylate monomer in a ratio of 91:1-70:30, and 64:34-43:57 to obtain copolymers Aa and Ab, respectively, adding copolymer Aa and Ab into nanoparticle dispersed in organic solvent to form mixed solutions of Ba and Bb, respectively, spraying the mixed solutions of Ba and Bb using electrostatic spinning machine through nozzle, then carrying out electrostatic spinning process with mixed solutions flow rate of 0.4 ml/minute, increasing or decreasing the flow rate at a constant amplitude, carrying out annealing treatment after spinning process, and then drying, is claimed. INDEPENDENT CLAIMS are included for:    (1) a gel polymer electrolyte comprising polymer film swelled in a electrolyte solution;    (2) a lithium ion polymer battery comprising a positive electrode, a gel polymer electrolyte, a negative electrode, and a membrane, where the gel polymer electrolyte is located between positive and negative electrodes; and    (3) preparing the lithium ion polymer battery comprising laminating the polymer film, a positive electrode and a negative electrode in three layers, putting pole core on the laminated material, injecting electrolyte solution through a pole core, and then sealing.