An acetylene black/poly amino benzene sulfonic acid modified electrode(AB/PABSA/GCE) was prepared using electrical aggregation and coating.The modified electrode was characterized by electrochemical impedance spectroscopy(EIS).The electrochemical behavior of vanillin(Van) on AB/PABSA/GCE was investigated by cyclic voltammetry(CV).The results showed that there was an obvious oxidation peak of Van on the modified electrode in pH 7.0 PBS buffer solution and the oxidation peak current was linear with the scanning rate in the range of 40-300 mV/s,which indicated that the electrode process of Van was irreversible and controlled by absorption.The electron number(n),proton number(m),effective area(A),diffusion coefficients(D) and the absorbance of reactant were calculated to be 2,2,0.065 7 cm2,1.557×10-3 cm2/s,2.249×10-8 mol/cm2 in the electrode reaction process.The different concentrations of Van were determined by chronoamperometry,and a good linear relationship between oxidation peak current and Van concentration was observed in the range of 5-460 μmol/L.The detection limit(S/N=3) was 2.09×10-7 mol/L.The method was successfully applied in the determination of Van in chocolate sample with recoveries of 93.0%-114.2%.