The invention relates to an environment-friendly rubber plastic heat-insulating material and its preparation method, and the rubber plastic heat-insulating material is prepared from butyronitrile rubber (NBR), antimonous oxide (Sb2O3), zinc oxide, sulfur, dioctyl-phthalate (DOP), epoxidized soybean oil (ADDA), mercaptobenzothiazole (M), anti-aging agent (4020), antioxidant (AST-500), protective wax (HGB-3), ethylene-vinyl acetate copolymer (EVA), dicumyl peroxide (DCP crosslinking agent), polyethylene glycol (PEG), stearic acid, aluminum hydroxide, foaming agent-dinitrosopentamethylene tetraamine (H), diphenylguanidine (D), pigment, anti-aging agent (RD), anti scorching agent (PVI), and the like. By limited use of raw materials containing chlorine ion components and cooperation of a new vulcanization foaming technology, environment-friendly and heat-insulating performances of the product can be stabilized, the prepared environment-friendly rubber plastic heat-insulating material has no corrosion performance in use, the material life is prolonged, metal pipes in refrigeration equipment can be effectively protected, and maximized performance of the product can be performed.