NOVELTY - A multi-layer crosslinked doped ion film comprises 2-40 layers comprising fluorine-containing ion exchange resin with an equivalent weight value of 600-1300, and has total thickness of 10-300 mu m. The layer(s) have crosslinked net-shaped structure; use a cellular film as the cellular reinforcing film; are added with an inorganic dopant with water protection function or proton exchange function; and can be porous reinforcing films using the cellular film.    USE - A cellular film reinforcing multi-layer crosslinked doped ion film for fuel batteries production.    ADVANTAGE - The ion film has improved mechanical strength, increased stability in length, width and thickness directions, high ion exchange capability, and high electroconductibility.    DETAILED DESCRIPTION - A multi-layer crosslinked doped ion film comprises fluorine-containing ion exchange resin with an equivalent weight value of 600-1300 and has 2-40 layers and total thickness of 10-300 mu m. The layer(s) have crosslinked net-shaped structure of formula (I), (II), (III), (IV) and/or (V); use a cellular film as the cellular reinforcing film; are added with an inorganic dopant with water protection function or proton exchange function; and can be porous reinforcing film using the cellular film. The film has conductivity is 40-150 mS/cm, and extension strength of 10-60 MPa. The inorganic dopant and fluorine-containing ion exchange resin are at mass ratio of 0.1-100:100, preferably 0.5-50:100.    G1, G2=CF2 or O;    Rf=2-10C perfluorocarbon chain or perchlorofluorocarbon chain;    R=methylene or perfluoromethylene; and    n=0-10.    An INDEPENDENT CLAIM is included for a method for preparing the cellular film reinforcing multi-layer fluorine-containing crosslinked doped ion film; comprising forming each layer of cellular film and fiber reinforcing multi-layer fluorine-containing crosslinked ion film by using fluorine-containing ion exchange resin and inorganic dopant solution; preparing multi-layer film through compositing single-layer; processing the films to form crosslinked structure of formula (I), (II), (III), (IV) and (V); and treating the formed product through alkali solution or acid solution. The crosslinked structure (I) is obtained through heat/light/electronic radiation, X ray, or free radical initiator, where the initiator is perfluoroamine organic peroxide. The crosslinked structure (II) and (III) are obtained through reacting Vikane(RTM: Sulfuryl fluoride), sulfonic acid chloride and sulfonic acid bromide type resin with ammonia, hydrazine, organic diamine, or substances which can release ammonia, hydrazine or organic diamine through chemical treatment. The organic diamine is 1-10C alkyl or fluorine-containing alkyl diamine. The substances which can release ammonia, hydrazine or organic diamine through the chemical treatment include (in)organic acid salt of ammonia, hydrazine or organic diamine, carbamide or guanidine. The crosslinked structure (IV) is obtained by treating chlorosulfonic acid. The crosslinked structure (V) is obtained by forming fluorine-containing sulfoacid resin, fluorine containing Vikane(RTM: Sulfuryl fluoride) resin, sulfonic acid chloride-containing resin or sulfonic acid bromide-containing resin containing nitrile group site under the action of heat or acid. The acid can be strong protonic acid such as sulfuric acid, trifluoromethanesulfonic acid, or phosphoric acid; or Lewis acid such as zinc chloride, ferric chloride, aluminum chloride, organic tin, organic antimony, or organic tellurium.