The invention discloses a preparation method for a composite highly-dielectric material. The preparation method comprises the following steps: weighing V2O5, Li2O and MgO, adding V2O5, Li2O and MgO into a ball mill, adding polypropylene glycol dimethacrylate, and carrying out mixing and grinding so as to obtain a mixture A; then placing the mixture A into a mold, and carrying out hot-press moldingso as to obtain a material B; adding the material B into an aqueous solution, and carrying out ultrasonic dispersion at a temperature of 35 to 45 DEG C for 10 to 20 min so as to obtain a suspension;preparing a uniform thin film on the surface of a substrate through a dip-coating method, and carrying out drying so as to obtain a first layer; adding graphene oxide powder into absolute ethyl alcohol, and carrying out uniform ultrasonic dispersion so as to obtain a graphene oxide suspension; preparing a uniform thin film with a thickness of 60 to 90 nm on the surface of the first layer through the dip-coating method, and carrying out drying so as to obtain a second layer; and repeating the above-mentioned steps for a plurality of times so as to be able to obtain the composite highly-dielectric material.