The invention relates to the technical field of nanometer materials, and relates to a metal/dielectric material compounded nanometer array structure and a manufacturing method thereof, in particular to a surface-enhanced raman substrate and a preparation method thereof. The raman substrate is of a nanometer array structure consisting of metal and a dielectric material, and the nanometer array structure is 10 to 25 nanometers in linear width. By adopting the surface-enhanced raman substrate, processing and preparation of the surface-enhanced roman substrate which has large area, uniform and controllable hotspot size distribution, and high sensitivity can be realized.