Metallic nanoparticles can be synthesized by photochemical reduction method with controllable shape and size, hence the photochemical reduction method has become one of the hot topics in the area of metallic nanoparticle synthesis. A method for fabricating large area metallic grating is provided. Gold nanoparticles are synthesized via photochemical reduction method. Nanoparticle gratings are deposited on the glass substrate under illumination of two coherent beams. Surface plasmon polaritons (SPP) are excited by the grating efficiently. The period and the surface features of metal-gratings can be controlled by adjusting the introduced light beams. After half hour annealing treatment under 400 ℃, the grating become smoother and the excitation angle of SPPs gets closer to the theoretical value.