Silver nanocubes synthesized by hydrothermal-Induced method were prepared into substrates using two different methods. The morphologies of these two substrates were different from each other. On one substrate, the nanoparticles congregated into congeries which were monodisperse, but another was a continuous film. SERS activities of silver substrates were detected by using RhB as probe molecule The results showed that the former has better SERS activity. The mechanism of SERS effect was also discussed.