The invention discloses a preparation method of a porous silicon/tungsten oxide nanowire composite structure for a gas-sensitive material, which comprises the following steps: with p-type monocrystal silicon as a substrate, preparing a porous silicon layer on the surface of the substrate by a double-groove electrochemical process; with metal tungsten as a target material, depositing a metal tungsten film on the surface of the porous silicon by a magnetron sputtering process; finally, in a horizontal tubular furnace, preparing a gas-sensitive material with a porous silicon/tungsten oxide nanowire composite structure at 600-750 DEG C by taking argon as a working gas and oxygen as a reaction gas. By adopting the method disclosed by the invention, the growth temperature of the prepared tungsten oxide nanowire is reduced, the specific surface area of the gas-sensitive material with a composite structure is remarkably increased, and the sensitivity on the 2ppm NO2 at 150 DEG C is 4.76; the method has the advantages of simple preparation process, easiness in control, low cost, high-sensitivity detection on NO2 and the like.