Abstract: Provided is a method for preparing polyacrylonitrile-methyl methacrylate gel electrolyte film. The method comprises the following steps: dissolving polyacrylonitrile-methyl methacrylate in an organic solvent with the mass 1 to 3 times as high as that of polyacrylonitrile-methyl methacrylate, adding MCM-48 mesoporous molecular sieves with the mass 0.05 to 0.3 times as high as that of polyacrylonitrile-methyl methacrylate, heating the mixture to 30-50° C., stirring them uniformly, and obtaining a slurry containing MCM-48 mesoporous molecular sieve; coating the slurry onto the substrate, vacuum drying, and obtaining a mesoporous molecular sieve MCM-48 modified polyacrylonitrile-methyl methacrylate gel electrolyte film. In addition, the corresponding electrolyte and its preparation method are also provided. The polyacrylonitrile- methyl methacrylate gel electrolyte modified by mesoporous molecular sieve MCM-48 has high electrical conductivity and good security.