The invention discloses a rubber-plastic-blended high-flame-retardant thermal-insulation material. The material is composed of a rubber-plastic blended material, a stabilizer, a filler, a plasticiser, a foaming agent, an active agent, a vulcanizing agent, an antiaging agent and a flame retardant. The heat-preserving material provided by the invention has weatherability and aging resistance of rubber, strength and plasticity of plastic, excellent flame retardant property and capability of being used as a heat-preserving, heat-insulating and sound-insulating material and applied in the engineering fields of building, transportation vehicles, ships, aerospace, etc.