Surface-enhanced Raman scattering (SERS) technique can be applied to enhance the electric field intensity at some locations (hot spots) on the metal surface. In this paper, the feasibility for silver dimer to be a substrate for super-resolution SERS imaging is researched. According to the finite-difference time-domain (FDTD) method, the electric field distribution of silver dimer under excitation light of different wavelengths and polarization directions are calculated and studied. The results show that the electric field distribution of silver dimer is highly localized, and the electric field intensity of hot spots in silver dimer can be controlled by the polarization direction of excitation light, which make it an effective substrate to realize super-resolution Raman imaging.