Size-controllable nanostructure fabrication has drawn much of research attention lately, because it may allow the tuning of optical, magnetic, catalytic and electric transport properties of materials. To achieve this goal, we need to investigate the size dependent behavior of materials. The most popular method for size-controlled nanostructure fabrication is e-beam lithography. However, e-beam lithography is not an efficient process for large area fabrication. We report here a novel method to produce large area, well-ordered, size-controlled nanopillar arrays. Nanopillar arrays are among the most studied nanostructures because of their potential applications in photonic crystals, data storage, and sensors. To fabricate nanopillar arrays, we have employed both single layer and double layer nanosphere lithography. Nanosphere lithography, which uses the close packed structure formed by monodispersed colloidal particles as template, is known to produce large area, well-ordered nanostructures on substrate surfaces. These nanostructures have been utilized as the masks in the reactive ion etching process. By carefully controlling the gas composition and etching time, various sizes of nanopillar arrays have been produced. To characterize the optical properties of these nanopillar arrays, surface nonlinear spectroscopy has been used to investigate the size dependent response of nanopillar arrays.