In　this　study,　we　successfully　constructed　Ag/TiO2　core-shell　nanoparticles　through　an　easy　wet　chemistry　method　for　SERS　study.　Compared　to　Ag　cores,　the　Ag/TiO2　core-shell　nanoparticles　presented　higher　SERS　sensitivity,　owing　to　a　synergistic　SERS　enhancement　arising　from　electromagnetic　field　effect　of　Ag　cores　and　chemical　enhancement　of　TiO2　shells.　Furthermore,　uniform　TiO2　shells　were　able　to　effectively　protect　the　internal　Ag　cores　against　destruction　in　external　environment　and　thus　storage　stability　of　Ag/TiO2　nanoparticles　was　prominently　improved.　The　as　prepared　Ag/TiO2　core-shell　nanoparticles　were　applied　to　quantitatively　sense　tetramethylthiuram　disulfide　(TMTD)　in　solution　using　a　portable　Raman　spectrometer.　The　results　showed　that　the　SERS　intensity　of　563　cm(-1)　assigned　to　S-S　stretching　mode　had　a　good　linear　relationship　with　the　concentration　of　TMTD　with　the　correlation　coefficient　(R-2)　of　as　high　as　0.99　and　the　detection　limit　of　as　low　as　1.15　x　10(-10)　M.　Consequently,　the　prepared　Ag/TiO2　nanoparticles　present　specially　advantage　of　quantifying　SS　groups　by　SERS,　because　the　TiO2　shell　could　act　as　a　spacer　between　Ag　cores　and　TMTD　molecules　and　keep　the　S-S　bonds　intact.