A new modified electrode（CS-AB/GCE）prepared with acetylene black and chitosan was used to determine naphthol isomers.The properties of electrode surface were characterized by SEM and Nyquist plots.The electrochemical behaviors of α-N and β-N on CS-AB/GCE was studied by cyclic voltammetry（CV）.Influences of type of buffer solution， ratio of CS to AB，amounts of CS and AB，pH value，concentration of naphthol isomers and scan rate were discussed.The results indicated that there were two oxidation peaks respectively belonged to α-N and β-N in pH 7.0 PBS buffer.The oxidation peak currents of both α-N and β-N were linear with scan rate（v） in the range of 20-200 mV/s，which showed that the electrode processes of α-N and β-N were controlled by adsorption.Some important parameters for these electrochemical processes were also determined.The effect area（A），electron number（n） and proton number（m） of the modified electrode were obtained to be 0.390 2 cm2，1 and 1，respectively.The adsorption capacity were 2.788×10-9 mol/cm2 for α-N， and 5.603×10-9 mol/cm2 for β-N.Under the optimal conditions，the differential pulse voltammetry（DPV） with derviative technique was used to determine naphthol isomers quantitatively.Good linear relationships between peak currents and concentrations of α-N and β-N were observed in the range of 2.5×10-6-1.0×10-4 mol/L，and the detection limits（S/N=3） were 3.4×10-7 mol/L for α-N and 2.4×10-7 mol/L for β-N.The proposed method was applied in the determination of α-N and β-N in water samples with spiked recoveries of 96.7%-105.1% and 98.8%-103.9%，respectively.