The invention provides a foam material for a shoe, a preparation method and application of the foam material. The foam material is prepared by sequentially performing the processes of injection molding and supercritical fluid foaming molding on a nylon elastomer composite material, and the nylon elastomer composite material comprises the following components in parts by mass: 50-100 parts of nylonelastomer resin, 0-50 parts of thermoplastic elastomer resin, 0.5-3 parts of a nanometer nucleating agent, 0-0.6 part of an antioxygen, 0-1.2 parts of stearic acid and 0-0.6 part of a foaming stabilizer. The foam material for the shoe has nanopores, is relatively light in weight, is endowed with relatively high hardness, further has the advantages of high resilience, low compressive deformation,relatively high tensile strength and the like, greatly reduces the weight of a sneaker and also is also relatively excellent in mechanical property and durability when used as an insole material of the shoe. In addition, the insole material of the shoe is prepared by rapidly releasing the pressure and foaming after dipping in supercritical fluid, the preparation flow is shorter, and the efficiencyis higher.