The invention discloses a fire-retardant cable sheath material formulation and the preparation method thereof. The formulation comprises, by weight parts, 15 to 30 parts of chloroprene rubber, 15 to 30 parts of chlorinated polyethylene, 0.5 to 3.0 parts of zinc oxide, 0.5 to 3.0 parts of magnesium oxide, 0.2 to 1.0 parts of ethylene thiourea, 0.5 to 2.0 parts of dibenzothiazyl disulfide, 0.1 to 0.5 parts of tetramethylthiuram disulfide, 0.5 to 2.0 parts of N-phenyl-2-naphthylamine, 0.5 to 2.0 parts of stearic acid, 0.5 to 3.5 parts of paraffin, 1.0 to 5.0 parts of dioctyl phthalate, 5.0 to 15 parts of carbon black with high abrasion resistance, 5.0 to 15 parts of semi-reinforced carbon black, 3.5 to 10 parts of calcium carbonate, 2.5 to 8 parts of bis(pentabromophenyl) ether, 1.0 to 3.0 parts of antimony trioxide, and 1.0 to 8.0 parts of aluminum hydroxide. The preparation method mainly comprises the following steps: plasticating, blending, mixing, thin-passing and calendaring and extruding the sheath.