The invention discloses a flexible metamaterial composed of spiral gold nanoparticles, and a preparation method and an application thereof, wherein the flexible metamaterial adopts a flexible spiral metamaterial as a substrate and gold nanometer particles are formed on the substrate. The flexible metamaterial takes the spiral metamaterial ITO membrane as the substrate, and is formed by assembling the gold nanoparticles by a layer-by-layer self-assembly method; the flexible metamaterial has the resonance characteristics at microwave frequency bands, and an obvious resonance peak can be detected in a specific frequency band, so a feasible way is provided for in vivo biological detection by an electromagnetic field.