Surface enhanced Raman scattering (SERS) refers to the phenomenon that the Raman scattering signal of some molecules will be significantly enhanced when they are close to or adsorbed on the surface of the substrate. SERS overcomes the weakness of Raman scattering signal intensity, and has been widely used in the fields of environmental detection, catalytic chemistry, organic chemistry and life science. In this paper, quantum chemistry method was used to simulate the SERS spectrum of molecules and study the SERS enhancement mechanism. Using the quantum chemical calculation method of density functional theory, the adsorption behavior and SERS enhanced effect of thiamethol and gold clusters were used to systematically study from the theoretical point of view, and the optimal adsorption position of gold clusters on thiamethol molecules was obtained. Five adsorption models were used to study the interaction between thiametrin-Au₄ and gold clusters. The results showed that thiametrin-Au₄ was the most stable. Combined with the Raman spectra and results of theoretical calculations, the vibration mode, Raman spectra and SERS spectra of thiametrin molecules were systematically identified by using the graphical function of Gaussview.