Surface-enhanced Raman scattering (SERS) has great application prospects in the fields of medical diagnosis, food safety, and environmental monitoring because of its sensitivity as high as single-molecule detection. Preparation of SERS substrates with high-density "hot spots" is the key to the practical applications. Nanoporous metals with bicontinuous structures have excellent SERS enhancement properties due to the coupling effect between neighboring nanostructures. Ag-Zn alloy precursors were prepared by sputtering method, and silver substrates with nanoporous structure were prepared by free dealloying process and electrochemical dealloying process. Through the modulation of dealloying parameters, SERS substrates with high enhancement factor were obtained. The detection limit of crystal violet reached 10^-12mol/L, which could be used for ultrasensitive detection.