NOVELTY - Preparation of an active gel-type lithium ion battery polymer electrolyte film comprises purifying a polymer's monomer by mixing with acrylonitrile and vinyl acetate; adding the polymer's monomer and crosslinker to a mixture of polyvinyl alcohol and deionized water, and adding initiator; filtering, washing off unreacted monomer with ethanol, and sweeping with nitrogen gas; dissolving in N,N-dimethyl formamide and/or acetone, coating on a glass plate, soaking in a water bath, naturally drying to obtain a polymer matrix film; and soaking in an activated gel, and blasting.    USE - Method for the preparation of an active gel-type lithium ion battery polymer electrolyte film (claimed).    ADVANTAGE - The method has short reaction time.    DETAILED DESCRIPTION - Preparation of an active gel-type lithium ion battery polymer electrolyte film comprises:    (A) purifying a polymer's monomer by mixing with acrylonitrile and vinyl acetate or with acrylonitrile and methyl methacrylate;    (B) adding 0.1-0.5 wt.% polyvinyl alcohol to 60-69 wt.% deionized water in nitrogen atmosphere, stirring at 400-500 rpm for 10-15 minutes, uniformly dispersing, adding 30-39 wt.% polymer's monomer and 0.1-0.5 wt.% crosslinker, uniformly stirring, adding 0.1-0.5 wt.% initiator at 60-70 degrees C, and keeping the reaction for 6-8 hours to obtain a white emulsion;    (C) filtering the white emulsion, washing with 3 times water, washing off unreacted monomer with ethanol and deionized water at a weight ratio of 1:1, with acetone and deionized water at a weight ratio of 1:1, and sweeping with nitrogen gas at 60 degrees C to obtain a polymer matrix material;    (D) dissolving 15-30 wt.% polymer matrix material in 70-85 wt.% N,N-dimethyl formamide and/or acetone, stirring to obtain a thick gel, coating the gel on a glass plate via a film coating machine, soaking the film in a water bath to obtain a polymer film, taking the polymer film out from the water bath after 1 hour, naturally drying for 1 hour and in vacuum at 60 degrees C for 12 hours to obtain a polymer matrix film;    (E) dissolving 1-8 wt.% polymethacrylate, poly(2-hydroxyethyl methacrylate), or polyethylene glycol oxide in 92-99 wt.% N,N-dimethyl formamide, and stirring at 60-70 degrees C to obtain an activated gel; and    (F) soaking the polymer matrix film in the activated gel for activation, taking it out after 5-15 minutes, and blasting at 60-70 degrees C to dry for 1 hour.