Abstract: Multilayer films composed of substituted heteropolytungstate anions(P₂W₁₇Ni) and cationic polydimethyldiallylammonium chloride（PDDA） were prepared on 4-aminothiophenol（4-ATP） modified glassy carbon electrode by electrostatic layer-by-layer adsorption.Cyclic voltammetry have been employed to monitor the deposition process of the multilayer films and study the electrochemical properties of the modified electrode.In buffer solutions,the multilayer films exhibit three one-electron redox processes.The peak current is linearly in proportion to the square root of the scan rate(v^1/2),which shows that the electrochemical behavior is diffusion-controlled.The multilayer film electrode has an electrocatalytic response to the reduction of BrO^-₃ and NO^-₂.