In this paper, we proposed a simple in situ method for the synthesis of pristine-graphene/Ag nanocomposites by chemical reduction of Ag ions in a N-methyl pyrrolidone solution in which pristine-graphene had been homogeneously dispersed. Ag nanoparticles can be directly attached on the pristine-graphene surface without any functionality. The obtained pristine-graphene/Ag nanocomposites are investigated by transmission electron microscopy, X-ray diffraction, and X-ray photoemission spectroscopy. The results show that Ag nanoparticles are homogeneously distributed on the pristine-graphene sheets with high density. We further demonstrate that this pristine-graphene/Ag nanocomposites exhibit a very strong surface-enhanced Raman scattering (SERS) effect, which can be used as ultrasensitive SERS substrates for chemical and biological analysis.