The invention relates to a power cable insulating layer material and a preparing method thereof. The material comprises, by weight, 70 parts of polyvinyl chloride, 3 parts of ethylene-vinyl acetate copolymer, 10 parts of polyvinylidene chloride, 10 parts of methyl vinyl silicone rubber, 15 parts of GNA type chloroprene rubber, 5-6 parts of epoxy fatty acid essien ester, 1 part of barium stearate, 10 parts of aluminum hydroxide, 5 parts of compatilizer, 8-10 parts of fire resistant systems and 0.1 part of antioxygen. The prepared fire resistant cable material is obvious in synergistic effect, good in antioxidant effect, high in stability and obvious in fire resistant effect, and has wide application prospects.