Silver and Gold nanoparticle have a characteristic of surface-enhanced Raman scattering (SERS). Poly(L-lysine) is a biocompatible polypeptide and can swell to the random coil in aqueous solution by grafted on silicon substrate. The amino group with positive charge can adsorb the nanoparticle to form the biocompatible nanocomposite film. This film can use as the substrate of surface-enhanced Raman scattering (SERS). We use Rhodamine 6G to find the best SERS and the effect of film to SERS.