In this paper,a rGO/NPAN composite film modified electrode was fabricated successively by electropolymerization，adsorption,and constant potential reduction method.Then,a MnO2/rGO/NPAN modified electrode was constructed by dropping the prepared manganese dioxide on the support material consisted of reduced graphene oxide and N-substituted carboxylic polyaniline.The strong adsorption of N-substituted carboxylic polyaniline and great surface area and high conductivity of reduced graphene oxide could make manganese dioxide loaded well and improve electrocatalytic properties of the MnO2/rGO/NPAN modified electrode.The morphology of the composite film was characterized by scanning electron microscopy(SEM).In addition,the factors such as the number of NPAN electropolymerization,GO concentration,electroreduction time and pH values,were discussed in terms of electrochemical activity and electrocatalytic activity.Experimental results showed that the modified electrode had a good catalytic effect to nitrite oxidation.Compared with manganese dioxide modified electrode,the MnO2/rGO/NPAN modified electrode had a lower detection potential,higher response current and sensitivity to nitrite in the concentration range of 0.5×10-6-5.13×10-2 mol/L,with a sensitivity of 14.075 μA?(mmol/L)-1 and the detection limit(S/N=3) of 0.2 μmol/L.