We present our recent progress in the design and fabrication of large-scale grain-shaped gold nanoparticle (AuNP) thin films using vacuum evaporation and annealing.The morphology and optical properties of the prepared AuNP thin films under different fabrication conditions were investigated systematically.We produced models for simulating extinction spectra of Au grains with predetermined morphologies.It is evident from practical experiment that the optical properties of AuNP films are closely related to their micro-morphology and the simulation further show the relationship between Au grain size and localized surface plasmon resonances (LSPRs).