We present a novel surface-enhanced Raman spectroscopy (SERS) substrate based on a double-deck hybrid system assembled by monolayer graphene and Cu nanoparticle layer. The monolayer graphene film was grown by chemical vapor deposition (CVD) technology. The Cu nanoparticles with a uniform distribution were synthesized by liquor-phase reduction synthesis (LPRS) method on the SiO2 (3 cm x 3 cm) substrate. By transferring graphene onto the Cu nanoparticle layer, we fabricated graphene/Cu nanoparticle hybrids (G/CuNPs) SERS substrate. The hybrid SERS substrate showed excellent Raman enhancement effect for adenosine. A reasonable linear response between the SERS intensity and adenosine concentration was obtained in the concentrations of 10(-2)-10(-6) M. This work provided amazing potential for sensitive label-free detection of biomolecular. (C) 2015 Elsevier B.V. All rights reserved.