The present invention relates to an electric cable material, particularly to a modified PVC electric cable material with characteristics of corrosion resistance and thermal insulation, and a preparation method thereof. The electric cable material is prepared from the following raw materials by weight: 50-60 parts of a PVC resin, 18-25 parts of a maleic anhydride-grafted ethylene-vinyl acetate copolymer, 20-28 parts of aluminum hydroxide, 16-22 parts of flue deposit, 4-6 parts of polyacrylamide, 6-9 parts of foam glass powder, 1-3 parts of 2-mercaptobenzimidazole, 10-12 parts of triethyl citrate, 1-2 parts of an accelerator DM, 1-2 parts of di-tert-butyl-p-cresol, 8-10 parts of a color concentrate, and 2-3 parts of an auxiliary agent. According to the present invention, the electric cable material adopts the PVC resin as the base material and is matched with the maleic anhydride-grafted ethylene-vinyl acetate copolymer, the flue deposit being subjected to the surface treatment through the polyacrylamide in the raw materials has characteristics of good dispersion property and uniform and stable reinforcing effect, and other remaining materials are combined, such that the electric cable material of the present invention has the excellent mechanical property, and further has advantages of significantly-improved heat resistance, strong corrosion resistance, uniform and stable performance, high raw material utilization rate, economy, and environment protection compared with the traditional PVC resin electric cable materials.