A　new　method　of　synthesis　Au/Ag　core/shell　nanostructure　with　KrF　excimer　laser　is　studied.　It　is　found　that　the　Au/Ag　core/shell　nanostructures　with　spherical　shell　can　be　prepared　by　KrF　excimer　laser　which　is　obviously　confirmed　by　high　resolution　transmission　electron　microscopy　(HRTEM).　The　surface　plasma　resonance　(SPR)　of　this　nanostructure　can　be　tuned　by　controlling　thickness　of　the　Ag　shell.　Simulation　based　on　Mie　theory　is　in　agreement　with　the　result　of　the　experiments.　Moreover,　it　is　indicated　that　the　Au/Ag　core/shell　nanostructure　has　excellent　activity　in　surface-enhanced　Raman　scattering　(SERS).　This　Au/Ag　core/shell　nanostructure　may　be　applied　to　high　sensitive　trace　detection　in　the　future.