We firstly discover the enhanced catalytic activity of magnetic noble metal nanoparticles mediated by surface plasmon resonance. Under light irradiation with certain wavelength, the catalytic performance of magnetic noble metal nanoparticles shows changes with different degrees and directions that are associated with the surface plasmon resonance (SPR) of the noble metal. Moreover, the coupling of silver and gold allows the catalytic performance of magnetic bimetallic Ag-Au nanoparticles to show more positive response to surface plasmon resonance. The magnetic bimetallic Ag-Au nanoparticles show excellent catalytic performance toward the reduction reaction of aromatic nitro group, and corresponding rate constant of the catalytic reduction reaction increases about three times with light irradiation.