The invention relates to a thin-wall insulated electric wire material for an automobile and a preparation method of the electric wire material, belonging to the technical field of materials, and solving the problem that cable wires cannot meet long-time ageing resistance, low-temperature resistance, high-temperature resistance, high physical performance, no drop during combustion, good liquid resistance and the like simultaneously in the prior art. The cable material comprises the following ingredients in parts by weight: 100 parts of matrix resin, 30-40 parts of modifier, 40-60 parts of plasticizer, 15-25 parts of filler, 50-60 parts of flame retardant, 5-10 parts of stabilizer, 1-5 parts of wear-resistant agent, and 1-5 parts of auxiliaries, wherein the plasticizer is the mixture of halogenated biphosphate compound FR-V6, dihexyl sebacate and 2,2,4-trimethyl-1,3-pentanediol di-isobutyrate in a weight ratio of (5-10): (3-6): 1. The thin-wall insulated electric wire material for the automobile disclosed by the invention is good in physical performance, resistant to long-time ageing, and low in cost.