Nanodisk array with both sandwich structure of Au/ [Co/Pt] n /Au and [Co/Pt] n were fabricated by electron-beam lithography combined with ion milling process. Optical transmittance spectra revealed the excitation of localized surface plasmon resonance (LSPR) in Au/ [Co/Pt] n /Au nanosandwich array. Magneto-optical (MO) properties were measured by a micro-Faraday system with objective lens design and laser source. Faraday rotation angle for sandwich structure increased considerably compared to that of [Co/Pt] n, indicating enhancement in MO activity by excitation of LSPR. The optical and MO properties of nanosandwich array were fitted in the framework of average field approximation.