The invention provides a high-polymer flame-retardant foam material and a method for preparing the same, and belongs to the technical field of foam materials. The high-polymer flame-retardant foam material comprises, by weight, 103-128 parts of polyvinyl chloride, 15-25 parts of EVA (ethylene vinyl acetate) particles with the vinyl acetate contents of 15%-22%, 65-80 parts of light calcium carbonate, 6-10 parts of foaming agents, 4-6 parts of silicone oil, 15-20 parts of flame retardant, 3-5 parts of flame-retardant synergists, 1-2 parts of cross-linking agents and 3-5 parts of foaming auxiliaries. The flame retardant is layered bimetal hydroxide, the flame-retardant synergists comprise graphene and isopropyl tri-(dioctyl pyrophosphoric acid amide epoxide) titanate, and a weight ratio of the graphene to the isopropyl tri-(dioctyl pyrophosphoric acid amide epoxide) titanate is 3-4:1. The high-polymer flame-retardant foam material and the method have the advantage that the high-polymer flame-retardant foam material which is a heat-insulation material prepared by the aid of the method is good in heat-insulation and flame-retardant property on the premise that certain strength of the heat-insulation material is guaranteed.