The invention relates to an interpenetrating network structure ion-exchange membrane and a preparation method thereof. The preparation method comprises the following steps: a perfluorinated sulfonic acid exchange resin and a polymerizable monomer containing proton exchange functional groups are dissolved by using a polar organic solvent; and casting film is formed on the smooth surface of a solidby using the tape casting method; the polymerizable monomer containing the proton exchange functional groups is initiated to generate polymerization reaction, and the products of the polymerization reaction and perfluorinated sulfonic acid molecular chains form the ion exchange membrane with the interpenetrating network structure. The preparation method of the ion exchange membrane can obtain ionexchange membrane materials with very good proton exchange property, overcomes the defects that the homogeneous cross-linked ion exchange membrane can not be prepared in the existing melt molding process, and has the advantages of simple technological process, easy industrial scale-up and the like.