The multi-walled carbon nanotube (MWCNT) was functionalized with hydroxyl, carboxyl and amido groups on the surface. Electrocatalytic oxidation of nitric oxide (NO) at the MWCNT modified electrodes was investigated. It was found that the MWCNT modified electrode could speed up greatly the electron transfer rate compared with the glass carbon electrode, and there was an adsorptive step for the oxidation of NO at the MWCNT modified electrode. The activation energy of NO electrooxidation reaction at modified electrode of MWCNT treated by alkali and mixed acids (MWCNT-OH-COOH) decreased, and current density was almost two times that of the electrode modified with alkali treated MWCNT. The modified electrodes of MWCNT amidated with the aliphatic amines decreased the activation energy of NO oxidation compared with MWCNT modified electrode, but the reaction rate of amidated MWCNT electrodes decreased because of the steric effect. The results demonstrated that MWCNT-OH-COOH modified electrode is the best for NO electrocatalytic oxidation.