A　highly　selective　and　sensitive　electrochemical　sensor　for　ascorbic　acid　(AA)　assay　has　been　prepared　through　Cu(I)　catalyzed　azide-alkyne　cycloaddition　reaction　(CuAAC).　The　catalyst,　Cu(I)　species,　is　acquired　from　the　reduction　of　Cu(II)　by　AA　in　situ.　In　the　presence　of　Cu(I)　catalyst,　the　azide　modified　Au　electrode　surface　is　shown　to　react　quantitatively　with　terminal　propargyl-functionalized　ferrocene　forming　1,2,3-triazoles.　The　electrochemical　response　of　propargyl-functionalized　ferrocene　modified　Au　electrode　surface　can　be　monitored　using　differential　pulse　voltammetry　(DPV)　technique.　Under　optimal　conditions,　it　is　found　that　the　current　intensity　has　a　linear　relationship　with　the　logarithm　of　AA　concentration　in　the　range　of　5.0　x　10(-12)　to　1.0　x　10(-9)　M.　Furthermore,　the　proposed　electrochemical　sensor　shows　a　good　stability　(RSD　4.2%),　high　selectivity　and　low　detection　limit　for　AA　detection.　In　addition,　it　also　demonstrates　that　the　proposed　sensor　can　be　applied　to　detect　AA　in　real　urine　samples　with　satisfactory　results.