Poly vanillin（PVN）-graphene oxide（GO） composite film modified glassy carbon electrode（GCE） is fabricated through a simple and controllable dropping and in situ electro-polymerizing method

which is denoted as NO

2

-

electrochemical sensor.Voltammetric investigations indicate that the PVN-GO film has good catalytic ability to the electrochemical oxidation of NO

2

-

.Surface morphology and conductivity of PVN-GO film are characterized with the aid of scanning electron microscopy and electrochemical

impedance spectra（EIS） technique

respectively.Under optimal detecting conditions

a wide linear response over the NO

2

-

concentration of 2.0 × 10

-8

-1.1 ×10

-2

mol/L is obtained with a low detection limit of 5.0 × 10

-9

mol/L.Properties of sensor are checked and results show that the sensor has merits of good stability and reproducibility

high sensitivity and selectivity when used for NO

2

-

detecting.The sensor is applied to determination of NO

2

-

in water sample from the South Lake and the analytical results are satisfied.