An enzyme-free amperometric sensor based on a heptadecapeptide possessing an electroactive ferrocene (Fc) linker as ferro-cene-Gly-Gly-Gly-Gly-Phe-Gly-His-Ile-His-Glu-Gly-Tyr-Gly-Gly-Gly-Gly-Lys-(CH2)4-dithiocyclopentane self-assembled on gold substrate was designed and fabricated for specific determination of L-arginine (L-Arg).The detection mechanism is based on conformational change of surface-immobilized peptide induced by the target L-Arg,which was confirmed via SEM,TEM,AFM,XPS,and SPR studies.The binding affinity and the recognition feasibility of immobilized specific and non-specific peptides were also assessed using elec-trochemical impedance spectroscopy (EIS),cyclic voltammetry (CV),and differential pulse voltammetry (DPV).The proposed method can serve as “signal-on” sensor for detection of L-Arg down to 31 pmol/L with broad linear range (0.0001 to 10 μmol/L).Furthermore,the Fc-conjugated specific peptide sensor was successfully applied to the determination of L-Arg in pig serums with a recovery rate of 97.5％-106.9％,and its test results are in good agreement with that of chromatographic instrument,evidencing that the oligopep-tide-based sensor can be served as a simple and enzyme-free biosensing platform towards L-Arg for future application.