MoS2-plasmonic hybrid platforms have attracted significant interest in surface-enhanced Raman scattering (SERS) and plasmon-driven photocatalysis. However, direct contact between the metal and MoS2 creates strain that deteriorates the electron transport across the metal/ MoS2 interfaces, which would affect the SERS effect and the catalytic performance. Here, the MoS2/graphene van der Waals heterojunctions (vdWHs) were fabricated and combined with two-layered gold nanoparticles (Au NP) for SERS and plasmon-driven photocatalysis analyse. The graphene film is introduced to provide an effective buffer layer between Au NP and MoS2, which not only eliminates the inhomogeneous contact on MoS2 but also benefits the electron transfer. The substrate exhibits excellent SERS capability realizing ultra-sensitive detection for 4-pyridinethiol molecules. Also, the surface catalytic reaction of p-nitrothiophenol (PNTP) to p,p-dimercaptobenzene (DMAB) conversion was in situ monitored, demonstrating that the vdWHs-plasmonic hybrid could effectively accelerate reaction process. The mechanism of the SERS and catalytic behaviors are investigated via experiments combined with theoretical simulations (finite element method and quantum chemical calculations).