NOVELTY - Lithium-ion gel electrolyte film (I) based on diene/ether copolymer comprises (in wt.%) a crosslinked diene/ether copolymer gel matrix (10-80), a plasticizer (15-85) and a lithium salt (2-5), where the thickness of the gel electrolyte film is 20-50 mu m.    USE - The film is useful for electrolyte film material of power lithium ion battery.    ADVANTAGE - The film: has high strength, since it has polyolefin and polyether two-phase micro-phase separation structure and the polydiene chain segment forms a crosslinked structure; provides a lithium ion transfer channel, since the plasticizer absorbs polyether and lithium salt; and has high conductivity and strength due to the presence of nonwoven fabrics.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) preparing the lithium-ion gel electrolyte film (I), comprising (i) dissolving diene/ether copolymer (20-80%) and an initiator (0.1-1%) into an organic solvent (19-79.9%) to obtain a film liquid, (ii) directly transferring the film liquid on a stainless steel or glass surface carrier, scraping the liquid film with a thickness of 20-50 mu m, evaporating the solvent to obtain a crosslinking diene/ether copolymer film, (iii) irradiating the crosslinking diene/ether copolymer film for 5-60 minutes by heating or in the presence of ultraviolet rays, crosslinking the double bond of the polymer and curing to obtain diene/ether copolymer gel matrix film, where the heating temperature is 50-100 degrees C, and the ultraviolet irradiation power is 100 W to obtain a crosslinked diene/ether copolymer gel matrix film and (iv) soaking the crosslinked diene/ether copolymer gel matrix film in a solution containing lithium salt (2-25%) and the plasticizer (75-98%) in the absence of water and oxygen for 10-120 minutes to obtain a lithium electrolyte film, sealing and preserving the film;    (2) a lithium-ion gel electrolyte film (II) based on diene/ether copolymer, comprising (in wt.%) a crosslinked diene/ether copolymer gel matrix (20-50), a plasticizer (30-60) and nonwoven fabrics (10-30), where the thickness of the gel electrolyte film is 30-60 mu m; and    (3) preparing the lithium-ion gel electrolyte film (II), comprising (a) dissolving diene/ether copolymer (20-80%) and an initiator (0.1-1%) into an organic solvent (19-79.9%) to obtain a film liquid, (b) directly transferring the film liquid on the non-woven fabrics, scraping the liquid film with a thickness of 20-50 mu m, seeping the film liquid through the gap of the nonwoven fabrics, evaporating the solvent to obtain crosslinking diene/ether copolymer film supported by the non-woven fabrics, (c) irradiating the crosslinking diene/ether copolymer film supported by the non-woven fabrics for 5-60 minutes by heating or in the presence of ultraviolet rays, crosslinking the double bond of the polymer and curing to obtain a diene/ether copolymer gel matrix film, where the heating temperature is 50-100 degrees C, and the ultraviolet irradiation power is 100 W to obtain crosslinked diene/ether copolymer gel matrix film and (d) soaking the crosslinked diene/ether copolymer gel matrix film supported by the nonwoven fabrics in a solution containing lithium salt (2-25%) and the plasticizer (75-98%) in the absence of water and oxygen for 10-120 minutes, seeping the lithium salt and plasticizer completely through the gel matrix for swelling to obtain a lithium electrolyte film, sealing and preserving the film.