The invention discloses a nano-modified polyurethane packaging material and a preparation method thereof, and relates to a composite material, a structural material and a preparation method of the composite material. The nano-modified polyurethane packaging material is prepared by the following steps: preparing a white material composition from modified graphene, polyether polyol, polyester polyol, a foaming stabilizer, glycerinum, water, cyclopentane, triethylene diamine (33% water solution) and stannous octoate; mixing with polyisocyanates; and heating and foaming, so as to prepare the nano-modified polyurethane packaging material. The nano-modified polyurethane packaging material is convenient to produce, manufacture and transport, low in production cost, good in buffer shock resistance, high in support strength, good in texture, light in weight, good in waterproofness, free of damage of worms, not easy to deform, free of a poisonous gas styrene, friendly to environment, and antistatic, and is capable of resisting interferences such as electromagnetic valves and radio frequency; and the method is suitable for fabrication of the packaging materials of instruments, equipment, electronic products, electric tools and the like.