The invention discloses a preparation method for a medium/metal-core/shell surface plasmon crystal. The preparation method comprises the following steps that sub-micron or micron polystyrene or silicon dioxide microspheres are arranged on an interface between water and air, and a two-dimensional hexagonal close-packed colloidal microsphere array is obtained; the colloidal microsphere array formed in the position of the interface is transferred on an underlayer with through holes, and the suspending colloidal microsphere array is obtained in the through hole area; a two-dimensional colloidal crystal with the suspending feature serves as a template, metal films are physically deposited on both the upper surface and the lower surface of the microsphere array, namely, the integral medium sphere/metal-core/shell surface plasmon crystal is formed in the through hole area of the underlayer. The preparation method for the medium/metal-core/shell surface plasmon crystal is simple in process, and the thickness of a metal shell layer in the medium/metal-core/shell surface plasmon crystal can be precisely controlled. The preparation method can be quite easily expanded into preparing of a more complex multi-layer shell/core plasmon 'onion' structure.