This article demonstrates an efficient approach to fabricate nanoparticles arranged in a periodic pattern over a large area. A nanoscale gold film coated on a silicon wafer substrate was sectioned into grids by focused ion beam machining. Through a thermal treatment, the film in a confined area transforms into a nanoparticle due to the surface tension effect of the melted gold film. By controlling the film thickness and the size of the confined area, a nanoparticle array with various particle sizes and interparticle spacings can be manipulated. This approach may have great potential applications in sensor chips and nonlinear devices.