A　novel　direct　readout　colorimetric　optical　glucose　sensor　strip　was　constructed　based　on　a　three-layer　film,　including　a　green-emitted　CdTe/CdS　quantum　dots　(QDs)　layer　as　a　stable　color　background,　a　red-fluorescent　platinum-porphyrin　oxygen-sensing　layer　and　a　glucose　oxidase　layer.　The　sensor　achieved　high　resolution　(up　to　0.2　mmol　L-1)　glucose　determination　with　a　detection　range　from　0　to　3.0　mmol　L-1.　A　＇glucose　ruler＇　which　acts　as　a　glucose　standard　colorimetric　card　was　obtained.　Glucose　concentration　could　easily　be　directly　readout　using　the　＇glucose　ruler＇,　which　made　the　glucose　determination　rapid,　convenient　and　easy.　The　effects　of　pH,　salinity　and　temperature　were　systematically　investigated.　The　prepared　sensor　was　finally　applied　for　glucose　sample　analysis,　compared　with　the　＇glucose　ruler＇,　accurate　results　could　be　directly　readout.　©　2009　Elsevier　B.V.　All　rights　reserved.