The invention relates to a preparation method for automobile seat sponge and belongs to the technical field of decorative materials. According to the preparation method, silicon hydrogen condensationreaction is utilized to prepare silicone rubber foam; methyl hydrogen silicone oil diffuses from internal water phase to external water phase till reaching an interface of oil phase and external waterphase and absorbs liquid silicone rubber on the interface; hydrosilylation and condensation reaction are performed under the action of platinum catalyst, so that the methyl hydrogen silicone oil is deposited on the interface, the coating of ethylene-propylene-diene monomer is finished and a microcapsule is formed; a silicone rubber main chain is formed through the alternative linking of Si-O-Si bonds; due to a special skeleton structure, and under the action of platinum catalyst, cross-linking reaction occurs between vinyl silicone oil and hydrogen-containing silicon oil, foaming gas hydrogenis generated by hydroxyl silicone oil and hydrogen-containing silicon oil so as to perform foaming reaction, polyethylene glycol is added, and hydroxide radicals in polyethylene glycol react with hydrogen-containing silicon oil, so as to form a silicone rubber foam material. According to the preparation method provided by the invention, the unique physical properties of silicone rubber are kept and the automobile seat sponge has the advantages of light weight, heat insulation, flexibility, rebound resilience, and the like.