The invention relates to a preparation method for a polymer film for food contact, and particularly relates to a preparation method for a film for a migration test in a food contact material migration model. Polymer grains and a to-be-detected migration object are added in an organic solvent in a certain ratio, and adequately dissolved to form a mixed solution with viscosity; a certain amount of the mixed solution is taken, and dripped on a polymer composite isolation pad with the diameter of 2-5 centimetres, or the polymer composite isolation pad is placed in a spin coater, the mixed solution is added in the spin coater, and the spin coater is started. The polymer composite isolation pad dripped or sprayed with the mixed solution on the surface is placed in an atmospheric environment, and after the organic solvent in the mixed solution is volatilized, the polymer film containing the to-be-detected migration object is formed on the polymer composite isolation pad. Different from blowing moulding, calendering moulding, tape-casting moulding or stretching moulding for a polymer film, the preparation method disclosed by the invention has the advantages that preparation for the polymer film can be finished on a substrate with small dimensions, and moreover, the thickness of the obtained polymer film and the content distribution of the to-be-detected migration object are uniform, thus laying the foundation of a parallel test in the further migration test.