Raman spectroscopy can quickly achieve non-destructive, qualitative and quantitative detection, and analysis the molecular structure of substances. Herein, a facile and low-cost method for preparation of highly sensitivity SERS substrates was implemented through the displacement reaction of copper foam immersed in AgNO 3 ethanol solution. Due to the 3D structure of copper film and homogenous displacement, the Ag-Cu substrate showed high performance SERS enhancement (1.25 × 10 7 ), and the lowest detection concentration for R6G reached 10 -10 Mol/L. For glucose detection, mixed decanethiol (DT)/mercaptohexanol (MH) interlayer was used to enable glucose attach to the substrate surface, and the limit of detection reached to 1 uM/L. SERS substrate makes the Ag-Cu SERS substrate promising for biological applications.