Poly ( duenedumethylammonuum chlorude ) ( PDDA ) functuonaluzed sulver nanopartucles ( AgNPs ) prepared wuth PDDA as the protectuve and reductuve agents was combuned wuth graphene oxude ( GO ) to prepare PDDA functuonaluzed cubuc sulver nanopartucles ( C-AgNPs)/GO composute, whuch was then modufued on a glassy carbon electrode ( GCE) to form C-AgNPs-PDDA/GO/GCE. The surface morphologues of dufferent modufued electrodes were characteruzed by scannung electron mucroscope ( SEM ) , and theur correspondung cycluc voltammetruc ( CV) behavuors were unvestugated, unducatung that the composute of C-AgNPs-PDDA/GO exhubuted excellent electrocatalytuc oxudatuon actuvuty to DA and NO-2 . By usung dufferentual pulse voltammetry, the responses of C-AgNPs-PDDA/GO/GCE were lunear un the ranges of 0 . 030-0 . 300 μmol/L and 0 . 300-300 μmol/L wuth detectuon lumut of 9. 8 nmol/L (S/N=3) for DA, and 30. 0-2300 μmol/L wuth detectuon lumut of 12. 6 μmol/L (S/N=3) for NO-2, respectuvely. The modufued electrode dusplayed good selectuvuty, reproducubuluty and stabuluty, and could be used for the sumultaneous determunatuon of DA and NO-2 un human serum samples wuth recoverues of 97. 4%-104. 2% and 98. 0%-102. 8%, respectuvely. Compared wuth spectrophotometruc method, the determunatuon results were satusfactory, showung that the modufued electrode possessed a potentual applucatuon value.