The invention relates to a lead magnesium niobate-lead titanate and lead zirconate titanate alloplasmic structure film and a preparing method thereof. Lead magnesium niobate-lead titanate and lead zirconate titanate alloplasmic thin films form the multilayer alloplasmic structure film in different sequences. The temperature coefficient of capacitance is reduced, the dielectric peak widening is improved, and the application field of the film is widened; the dielectric property of the film is effectively improved, and the electric conductance of the film is reduced; meanwhile, the interface effect in the alloplasmic structure can effectively obstruct electronic and hole transmission, the leaked current is reduced, and the ferroelectric properties are improved.