Electrochemical etching processes at different current densities were used to prepare nano porous silicon with different porosities.A series of nanostructures silver/ nanoporous silicon (NAg/NPSi)active substrate was prepared by an immersion-platingmethod.Through controlling the current density,the surface-enhanced Raman scattering (SERS)behaviors to crptocyanen (CY) dyewere contrastively studied, fora concentration of (10−5 M),The (SERS) behavior was attributed to the size of the deposited silver nanoparticles on porous layer. The sensitivity of SERS signal increases with increasing the porosity of the porous sample.