Abstract: Normal Raman Scattering (NRS) spectroscopy of salicylic acid (SA) and the surface-enhanced Raman scattering (SERS) spectroscopy of SA adsorbed on silver nanoparticles were obtained experimentally. Density functional theory (DFT) calculations at the level of B3LYP/6-31+G**(C、H、O)/LANL2DZ(Ag) were employed to optimize molecular configurations of SA and calculate the NRS spectroscopy of SA and the SERS spectroscopy by different adsorption configurations of SA adsorbed on silver nanoparticles. And the calculation results were compared with the experimental data. It indicated that calculation results using SA molecular adsorption configuration through carboxyl were much more matched with experimental values than these of using SA molecules adsorption configurations through both carboxyl and hydroxyl groups. At the end, comprehensive assignments of the vibration mode for SA were studied by the software of Gauss View. According to the identification analysis of SA molecular Raman peaks, it can be drawn that, in silver colloids, the SA molecule will be tipsily adsorbed on the surface of silver nanoparticles through the carboxyl