Plasmon-driven catalytic reaction (PDCR) as a part of photocatalysis has attracted immense attention. Due to the collective oscillation of free electrons at the surface of metallic nanostructures, the charge distributions store energy from the incident light that could transfer energy to molecules that promote photocatalysis. As an environment-friendly and green photocatalysis process, PDCR illustrates a brilliant future. In this study, the PDCR efficiency of photo-reducing 4-nitro-benzenthiol (4-NBT) dry film to p,p'-dimercaptoazobenzene (DMAB) in ambient conditions has been studied by using Ag nanodiscs (NDs) and Ag nanoparticles (NPs) as catalysts. The distribution of catalytic efficiency of 4-NBT to DMAB using an individual Ag ND catalyst has been illustrated using spatial Raman mapping. The result is direct evidence that the PDCR efficiency has a positive correlation with plasmon-induced electromagnetic field intensity. Additionally, time-dependent surface-enhanced Raman scattering (SERS) experiments reveal that the PDCR of 4-NBT to DMAB is reciprocal. The discovery in this research will aid to improve the PDCR performance and modulate the catalysis reaction for a high reduction of 4-NBT in industrial.