Since the observation of the surface-enhanced Raman scattering phenomenon in 1974, surface-enhanced Raman spectroscopy (SERS) has been applied to detect the spectral information of adsorbates on noble and transition metal surfaces. It is a powerful technique in surface science to reveal the nature of the chemisorption interaction and the surface chemical reaction process by analyzing the spectral information of adsorbates on the metal interfaces. It has also been applied successfully to study bio-molecules and single molecules on nanostructured metal surfaces. The electromagnetic field enhancement and the chemical enhancement are two of the most widely accepted enhancement mechanisms. Here, we presented some results from our groups of the related experiments and theories of surface-enhanced Raman spectroscopy.