Localized Surface Plasmon Resonance (LSPR) based gas sensor is a promising way to break the bottleneck of the sensing speed of traditional semiconductor gas senor for mobile robot use. In this study, we developed a two-dimensional gas visualization system based on LSPR phenomenon with Au/Ag nanoparticles for high speed and high spatial resolution sensing. The 9-hour silver growth on the surface of Au nanoparticles layer has been shown to reduce the influence of transmitted light (noise) on visualization while ensuring sensitivity. An invisible odor trace similar to letter 'U' with a line width of 3 mm was visualized by CCD camera through the LSPR sensor film. The intensity changes of the image every 1 second showed of the developed system's high response speed and spatial resolution.