A carboxylated multi walled carbon nanotubes modified glassy carbon electrode（c-MWCNTs/GCE） was fabricated,and the electrochemical behavior of vanillin was studied in 0.5 mol/L HCl using cyclic voltammetry.Results revealed that the modified electrode showed an better electrocatalytic activity toward the oxidation of vanillin by a significant enhancement in the current response compared with that of the bare glassy carbon electrode.The oxidation of vanillin at this electrode was irreversible and diffusion controlled.Under the optimum conditions,by second order derivative linear scan voltammetry,the anodic peak current showed a linear relation versus vanillin concentration in the ranges of 0.1-6.0 μmol/L and 6.0-100 μmol/L with a detection limit（S/N=3）of 0.02 μmol/L.Moreover,the modified electrode demonstrated a good reproducibility（RSD=4.6%） and a long term stability.This method was applied in the determination of vanillin in food samples with recoveries of 96.3%-104%.