Surface　enhanced　Raman　scattering　(SERS)　is　a　rapid　and　nondestructive　technique　that　is　capable　of　detecting　and　identifying　chemical　or　biological　compounds.　Sensitive　SERS　quantification　is　vital　for　practical　applications,　particularly　for　portable　detection　of　biomolecules　such　as　amino　acids　and　nucleotides.　However,　few　approaches　can　achieve　sensitive　and　quantitative　Raman　detection　of　these　most　fundamental　components　in　biology.　Herein,　a　noble-metal-free　single-atom　site　on　a　chip　strategy　was　applied　to　modify　single　tungsten　atom　oxide　on　a　lead　halide　perovskite,　which　provides　sensitive　SERS　quantification　for　various　analytes,　including　rhodamine,　tyrosine　and　cytosine.　The　single-atom　site　on　a　chip　can　enable　quantitative　linear　SERS　responses　of　rhodamine　(10(-6)-1　mmol　L-1),　tyrosine　(0.06-1　mmol　L-1)　and　cytosine　(0.2-45　mmol　L-1),　respectively,　which　all　achieve　record-high　enhancement　factors　among　plasmonic-free　semiconductors.　The　experimental　test　and　theoretical　simulation　both　reveal　that　the　enhanced　mechanism　can　be　ascribed　to　the　controllable　single-atom　site,　which　can　not　only　trap　photoinduced　electrons　from　the　perovskite　substrate　but　also　enhance　the　highly　efficient　and　quantitative　charge　transfer　to　analytes.　Furthermore,　the　label-free　strategy　of　single-atom　sites　on　a　chip　can　be　applied　in　a　portable　Raman　platform　to　obtain　a　sensitivity　similar　to　that　on　a　benchtop　instrument,　which　can　be　readily　extended　to　various　biomolecules　for　low-cost,　widely　demanded　and　more　precise　point-of-care　testing　or　in-vitro　detection.