A novel modified electrode was prepared by electrochemicaly cycling scanning the glass carbon electrode covered with a macroporous alumina membrane in a solution containing PPy and PMo 12O 3- 40. The reversibility of the cyclic voltammograms was improved obviously. The remarkable advantage of the modified electrode was the high sensitivity and favorable electrocatalytic behavior toward NO - 2. The peak current increased linearly with the concentration of NO - 2 in the range of 8.0×10 -7—0.01 mol/L. The detection limit of NO - 2 was 1.0×10 -9 mol/L. The polyoxometalates nanopaticles modified electrode exhibited almost the same electrochemical behavior after 7 d. It is indicated that the PMo 12-PPy/AGCE has a good reproducibility, stability and wide linearity range.